I'll try and help.....! ;D
First thing I do is re-size the photos I want to put in my gallery; if you don't do this, one photo will take up a lot of room and you will run out of space in your gallery, we only have so many MB each. I use a simple online re-sizer like this, reducing each photo by 50%;
http://www.ivertech.com/freeOnlineImageResizer/freeOnlineImageResizer.aspxSave the re-sized photos you want to post to a file on your computer, I use a 're-sized' file in 'My pictures' on Windows XP.
Click on the A4A 'Gallery' tab and click on 'members galleries'....you should find your avatar name listed if you have posted photos before, if you have never tried before, go to your 'profile' tab instead, and you will find a 'view gallery' link next to 'user images' on that page.
Under 'Gallery Admin panel' you can make different sections of your gallery, for example plot no.1, home garden, cats, etc. You can load a photo that will be shown for that category, fill in the title, description if you want one, then upload a photo; do this by clicking on the browse button next to 'upload gallery icon' you then find your re-sized photos on your computer, click on the one you want to use then click 'add category' button at the bottom.
Now you have a gallery category sorted, you can load your photos. Click into your category, and it has 'add a picture' at the bottom. Click that link and use the same method as you added a category to load each picture from your computer.
Simples! Hope this helps a bit. Have a look at my gallery to see how I have laid it out and added descriptions and titles of things, you can add subcategories as well if you like.....