Attaching photos can take some effort. It took me months of trying at first and then I got it down -- and then the boards changed formats! Some people still haven't gotten the kinks out but we have some good help stuff in here:
https://www.quiltingboard.com/qb-help-center-f27/
Photo stuff is stickied to the top.
If you are using a smart phone or device from this century, I can't help much but there are options and defaults and ways you can send things and people in those stickied threads can help.
For me, the problem is that I have an old school digital camera. It and its software is rather limited and the file sizes are huge. I go to this site to reduce the image.
https://www.reduceimages.com/
I drag from my file folder and simply use their suggested defaults and download from there.
When we attach files, it says that we have 5 MB to use, but I think that is for all 6 (or however many) attachment slots there is and each individual item must be much smaller.
The next thing that trips people up is once you have successfully browsed and it looks like you have attached your files, there is an "upload" button you have to press that is way off to the far right upper corner out of view range. Our old board format was vertically based and the frame size is still set for that instead of our newer more horizontal layout. You have to grab and stretch the outline of the window to see/use that upload button!
If you get the upload failed message, it is probably because an image was too large. Double check that you attach the reduced download file, from your download directory and not the original image.