Revising Headers and Footers

How do I change the information that is in the header when I’m compiling as an epub?

There is no concept of a header or footer in e-book publishing. You might be referring to whatever the reader software/device is adding to the page. You can’t control what the software does around the sides of the book. The presentation of the material you provide it is entirely up to the device.

Thanks AmberV.
As you can probably tell, I’m new to all this.