We have some great help on the Help page
https://www.quiltingboard.com/qb-help-center-f27/
Some are stickied to the top, and then there are other recent ones.
The two most common problems seem to be finding the upload button (stretch out window to the far right after you add your attachments), and if you get the "upload fail" button, that is usually that your file sizes are too large.
I have an old school digital camera and I reduce my file sizes here:
https://www.reduceimages.com/
I simply use their defaults and down load through there, then upload here.
No connection with the site other than I recommend it as being quick, simple, and easy to use while not setting off my various virus checkers and scanners.