Hi,
I think you need to have very clear understanding on
MasterPage
before using in your project, otherwise though your specified problem shall be solved now but you will face difficulty later in the project.
You will get very basic understanding and application of
MasterPage
in asp.net project from below link
http://www.dotnetperls.com/master-page[
^]
another tutorial
http://www.youtube.com/watch?v=epaavQsb950[
^]
And solution to your posted problem is simple, link those page with your menu item links. For example you have master page default.master , this page is used by 2 content page say, default1.aspx and default2.aspx. Now link these 2 pages with your menu link like,
<a href='default1.aspx'>menu item 1 </a>
<a href='default2.aspx'>menu item 2 </a>
Thats it, you are good to go. Hope this will help.