I got my custom avatar pic returned and MR custom asked it to resubmit it with 32x32 pixels!?
Explain please..
It means that the physical size of the image when it appears on the screen should be a squarish 32 pixels (width) and 32 pixels (height). If you open any image editing program like Paint/Photoshop/Irfanview…you can easily see the image attributes/image size and all of these programs have an option to resize the image by specifying your desired height and width.
Hope it helps. If it does not, you can pm me the link or your pic and i will resize it for you. :~)
*in a generous mood today 
32x32 is the maximum pic size. I think you can submit a small pic (one which is not square) too. :)