Pappy, there's quite a size restriction for avatars -- they are limited to:
"Note: The maximum size of your custom image is 80 by 80 pixels or 19.5 KB (whichever is smaller)".
Most normal pictures are much larger and have to be resized.
I use PAINT on my 'puter -- it's normally part of most Windows.
If you have PAINT open it up, go into FILE, choose OPEN in the drop down menu to get to your pics in Pictures or Documents.....(wherever you have them).
Open the correct folder and highlite the picture you'd like to resize -- click on OPEN at the bottom of the box to transfer that pic to PAINT.
From there it's easy peasy: just click on RESIZE at the top left side next to CROP and you'll see an option box to resize your pic.
Choose the PIXELS button and type in 80 on the horizontal box only. If you have ticked the MAINTAIN ASPECT RATIO it will automatically insert the proper ratio of pixels into the vertical box. (so your avatar won't be distorted).
Go to the FILE tab again and choose SAVE AS in the drop down box, click on JPEG option the SAVE AS box appears where you can identify the picture by name and then SAVE to an appropriate folder which then you can BROWSE to here in your CP.
Lots of steps but doable -- give it a try but if you cannot get it to work I'll sent you my email addy which you can attach it to and I'll do it for you. PM me with the request and I'll be glad to help.