of a problem. What is it exactly that you're finding difficult?
If you want your header to include a logo, and/or some fancy text you would do well to create the whole thing as a graphic - that way the font you use will appear in anyone's browser exactly as you designed it. If you don't do that the font will not display if a visitor doesn't have it installed on his/her machine.
You can use various applications to design logos and headers - PaintShop Pro is popular, as is my personal favourite, Ulead PhotoImpact - a much underrated application in my opinion.
Post back if you have specific difficulties, and we'll see what we can do to help.