Don't know how to start

You are dealing with a chicken and egg problem. First you need to install an operating system (OS) on your Raspberry Pi. There are two obvious choices, Raspberry Pi OS and OctoPi (which is a customized version of Raspberry Pi OS - Lite). The full RPi OS will most likely have the drivers needed to interface with your 7" touchscreen but the Lite version of Raspberry Pi OS (i.e. OctoPi) will not. I'm guessing that the touchscreen has two connections to the RPi, an HDMI connection and a USB connection, so on either OS, the screen will display something, a desktop on the full OS and the text console on OctoPi.

If you install the full OS then your 7" touchscreen is happy but you don't have OctoPrint installed for you. There are, however, instructions on how to do that manually.

If you start with OctoPi, then there are instructions (a script) to install the full desktop but you may still need additional drivers to get touch working on the 7" touchscreen.

In either case, the OS needs a network connection to proceed. Instructions to configure a network connection are included in either OS install, but they will be slightly different.

To communicate with OctoPrint (and complete the installation) you will need a browser. This is usually on a separate system and, of course, connects through the network to the RPi running OctoPrint. Another useful communication protocol is SSH. The client you use will differ depending on the OS of your separate system, but if that separate system is Windows, then PuTTY is the recommended client.

OctoDash, OctoScreen, and/or TouchUI are all applications to designed to communicate with OctoPrint using a touchscreen. They all require a working OctoPrint.

My suggestion would be to start with OctoPi, get OctoPrint configured and working using a separate system. Maybe even 3D print something. Then using SSH / PuTTY, etc. install the desktop and any drivers needed to make your touchscreen work, and then pick an application to use.

If you decide to go the full RPi OS route and install OctoPrint manually, you will most likely need a keyboard. I have a 7" touchscreen but its not connected to my RPi running OctoPrint. On that RPi, in addition to a keyboard, I ended up attaching a mouse because my fat fingers on a tiny 7" screen didn't make for the most accurate pointing device. Eventually, I was able to use a bluetooth keyboard and bluetooth mouse which freed up 2 USB ports.

The people on this forum have more OctoPi / OctoPrint experise than 7" touchscreen expertise.

Thanks for your excellent input, Brad. I was contemplating installing the full RPi OS and then the OctoPrint app but I'm waiting to see if the seller, or a manufacturer, will give me the driver and spare me the trouble.

I too have a BT keyboard connected to my Pi otherwise I wouldn't have been able to do all the driver and app installing that I had to do to get OctoDash installed on my Pi.

Every thing is fine with my installation, so far, except the touch. Once I'll have that solved, either by getting the driver or going through the RPi OS I'm sure everything will be just fine and dandy but...should I then run into problem I will, for sure, come back and ask my silly questions! LOL

With a second SD card and a USB SD reader (or a USB thumbdrive) you could install RPi OS on the second SD card and copy the driver onto the OctoPi SD card. I'm surprised you didn't (can't) get driver installation instructions for the touchscreen. I got them with mine.

You know what, now that you've mentioned it, I'll do just that, I'll make a second SD card with the RSPi image and try it. Maybe then I'll also be able to see why the wifi is not working.

As mentioned before, the reason the drivers are not 'included' is that it is assumed that I will be using the RSPi image and not the OctoPi since the screen is supposed to work with the RSPi image.

EDIT: Just got a message from the seller on AliExpress that he can't get me the drivers and will refund me the money. Second SD card here I come :smiley:

What brand of 7" touchscreen did you buy? With the kind of support you are getting, I want to avoid it.

The one I have came in a nice box, lots of accessories, and an email address to contact for support.

I bought this one: 1024x600 Portable 7 Inch Touch HDMI Display Touch Screen Panel hdmi raspberry display LCD DIY Monitor HD Display Pc monitor|LCD Monitors| - AliExpress

Which one did you get?

BTW, I used to have a RSPi image on a SD card but I stopped using the Pi and put the card away. When I burned the OctoPi image I thought I burned it on that card. Turned out I didn't and I still had the other card with the original image. I inserted it but didn't have a touch on the screen. I did the updated and upgrade, which took a long time, and after reboot I still don't have touch. I'll keep looking into it but I'm glad I'm getting my money back.
2 more observations. 1, the RSPi image boots up way faster than the OctoPi image. 2, I have wifi on the RSPi image but I can't get the wifi on the OctoPi image. I may have to try to activate/install the desktop on the OctoPi and see why I don't get the wifi.

I bought this one:

Did you have to install drivers for it to work with OctoDash or did it work out of the box?

I didn't see in any of the videos the instruction to install the OctoPrint-TouchUI. Do I have to install it in order to get touch in OctoDash?

No, TouchUI and OctoDash are separate apps.

The OctoPi image is Raspberry Pi OS Lite, so it should generally work the same. Most touchscreens that connect using USB do come with driver installation instructions - it's only the ones that connect to the DSI port that I've seen work flawlessly out of the box, such as the official touchscreen from RPi. I'm surprised you didn't get instructions, and if they can't give you any help it seems worthwhile getting the money back.

I don't know. I bought it (along with an RPi 4B) for another project. What I do know is that the documentation included an email address,

@JustinTime, I have a better answer... I have a spare RPi 3B that isn't doing anything (it was running an old version of OctoPi / OctoPrint) so I installed a fresh OctoPi (0.18.0) / OctoPrint (1.7.2). Connected my 7" touchscreen, a USB keyboard, and when through the OctoPrint setup. Then (using SSH so I could cut and paste) I installed OctoDash. Aside from the fact that I don't have a 3D printer attached, all appears to be working including touch.

To put this baby to rest here is the latest.

I had tried the screen on a Raspbien image and it didn't work. I tried it on a Windows 10 PC and it didn't work.

I bought another screen, this time a Waveshare (C) on and it arrived yesterday and worked like a charm. PNP with no problem both on the Raspbien image and on the OctoPi image with OctoDash.

The seller, on AliExpress, already refunded me the money.