Sizing image for banner in template

[jamesg6]

Hi, Not sure if this is the right location for this thread. When I try to size my image to replace the banner image in a template, it never seems to work out right. I've gotten the pixel size of the banner image, but my image either gets squashed or repeats. What I'm trying to do is add a long thin image in a template, like av198. There doesn't seem to be any way to control what it does to the image.
any ideas?
Thanks!