The main reason pictures do not load is because their 'file size' is too big - in other words, with the advent of beautiful crisp, clear High Definition, referred to as 'HDR' on iPhones/iPads, the picture is simply too 'big' (uses too many pixels). Simply clicking on the little tree icon and then selecting 'Choose File' will simply not work - no matter
how many times you try, lol. It doesn't matter if you do it from the icon or 'Advanced'. Ain't going to work!
If you're using an iPad or phone, going in to 'Settings', then 'Camera' and turning off the HDR setting should work. Retake your picture and you should be fine.
If you're trying to upload a picture from your computer you already have - then it's the same - your picture 'size' is too big and you will have to resize, i.e. make it smaller.
Probably the best way for you to find out how to resize is to 'Google' it, as it will depend on what photo viewing programme your computer uses, but I'll tell you how I do mine.
First, open up the picture as you would normally, then right-click and the drop down menu appears. I select 'Open With' and a list of Photo programmes appears. I use Microsoft Office.
Once you've opened a likely looking programme, you need to find the 'Edit' or better, 'Edit Pictures' menu, usually along the top. Click and scroll down to 'Resize'. In the new box that opens on the right, I then choose 'Resize' under the 'Change Picture Size' heading. I change the size to 75% of the original. You then have to 'Save' before you close.
If you don't want to change the original size of your photo permanently, make a copy before you start. It probably won't matter too much if you do change your original, unless you're enlarging your photo to later to print as a poster. If you right-click on your photo and scroll down the menu until 'Properties', this will tell how big your file is. If you make a mental note of this, you'll then be able to check if you've managed to make it smaller or not.
Good luck - looking forward to seeing those quilts!
