Headers can be designed in so many ways. If there is a logo involved they are designed around allowing that logo
to stand out and be noticed.
It is also a place where any 'sales' comments can be made regarding what you do or sell.
Some use it for advertising, some place a search function, etc.
Decide what orientation you prefer.
Do you like things centered?
On the left?
Simple on white background, Logo and comment?
Graphic image with logo incorporated into the graphic?
There are endless ways of doing this, but for now let's just get a feel for what you lean towards.

Left

Centered

Right
So what do you like?