Alright, well, difference between sigs and banners is that the signature is for your posts and banners are for forums, and also banners are thinner. The little image to the left is called an avatar. As for controlling the pixel count, I can only tell you how to change it in Gimp, which is when you make a 'New' image type in 250 to the length and width bars. I'm assuming Photoshop has a similar set up. A big thing to remember about making banners, signatures or avatars is that when you resize a image/render, be completely sure that you scale the image. You don't want to distort it.