It depends which document class you are using.
If you are using document class memoir you please have a look to the question simple footers with only a page number. Document class memoir has its own header and footer mechanismn.
If you are using KOMA-Script, for example scrbook, you should use the KOMA-Script package scrpage2.
If you are using the classical document classes, for example book, you can use fancyhdr or scrpage2.
Meanwhile KOMA-Script has changed and was updated. The package scrpage2 has now changed to scrlayer-scrpage with more possibilites. I changed the following MWE to use the new package scrlayer-scrpage (only the call of the package has to be changed) instead of the old version scrpage2 (I only commented the call).
MWE for the usage of scrpage2 or scrlayer-scrpage (just move the comment sign to change the loaded package...):
\documentclass[
fontsize=12pt %
,english %
,headinclude %
,headsepline % line between head an document text
%,BCOR=12mm %
]{scrbook} % twosided, A4 paper
\usepackage[latin9]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{babel}
\usepackage{blindtext} % provides blindtext with sectioning
%\usepackage{scrpage2} % header and footer for KOMA-Script, old version
\usepackage{scrlayer-scrpage} % header and footer for KOMA-Script
\clearscrheadfoot % deletes header/footer
\pagestyle{scrheadings} % use following definitions for header/footer
% definitions/configuration for the header
\rehead[]{This is my name} % equal page, right position (inner)
\lohead[]{This is my name} % odd page, left position (inner)
\lehead[]{this is page \pagemark} % equal page, left (outer) position
\rohead[]{this is page \pagemark}
% definitions/configuration for the footer
\cefoot[]{center of the footer!} % equal page, center position
\cofoot[\pagemark]{\pagemark} % odd page, center position
\begin{document}
\Blinddocument
\end{document}