How do I change header size?

[david01130]

I have been trying to adjust a picture size in my header for hours. I basically have this purchased template with their default logo in the top left corner. I wanted to raise the height of the header and add my own image. I was able to raise the height in additions.css file, but when I add my own image it forms to the same height as the original header. When I try to move my image around it still is formed to that same height. How do I change the height of that image file? The image I am using is much larger but it continues to be cut down to the previous image's height. I have messed around with additions.css, header, and stylevars files but nothing works.