Sure buddy. If you're running windows, bring the picture up in the Paint program... bmp, jpg, gif. You can bring-up the "Image" button... hit "Attributes" slide to see the pixels that it's currently at... then hit the "Stretch/Skew" slide to shrink it down. You'll need to do the math to have it fit the required size for this site.

Make sure to "Save As..." a jpg or gif. Jpg's are often smaller in size, and will fit the site requirements better.

That's the best that I can help without knowing your programs.