There's 2 things you can do:

1. When you click Add Photo then Browse on webshots and the screen comes up to choose your photo, check below the file name box and select the All Files option in the drop down menu. Then all your files should show up so you can select one.

2. Open the gif in an image viewing program and do Save as. Choose jpg from the drop down menu where it says 'Save as type'.

Hopefully one of those ways will work for you.