Please help me, with editing my style

[Freesteyelz]

If you're familiar with HTML, the easiest way is to set a <div> wrapper/container code (1 or 2 depending on your needs) in the header and ending </div> tags in the footer.

Then in the Admin CP --> Style & Templates --> Style Manager --> All Style Options --> Main CSS at the very bottom you can add additional CSS definitions. Add the values for the <div> tag(s) there.