Welcome aboard! Posting pictures here can be harder than making a quilt! We do have some good help stuff here:
https://www.quiltingboard.com/qb-help-center-f27/
The boards changed formats earlier this year and some people are still having problems, you are by far not the only one!
It took me a surprisingly long time to figure out once I uploaded the pictures, I had to extend that box way out to the right to get to the needed button. My other problem is that I have an old school digital camera and my file sizes are always too large, camera is old and it's software isn't all that great either, so I go to this site to reduce my file size:
https://www.reduceimages.com/
I just follow their prompts and defaults. it's like 2-3 clicks.
Even if your picture is less than what they say is the maximum, I think that is for multiple images. Individual images/files still need to be on the small side.