If you need to pass data to a variable from content page to master page

you have to create a property in master page.

Create a property in your master page:

protected static string _master = "home";

public string Section
{   get
   {
      return _master;
   }
   set
   {
       _master = value;
   }
}

After creating a property in a master page you have to add a directive in

the child or content page.

Add page directive to your content page:

<%@ MasterType VirtualPath="~/MasterPage.master" %>

After creating   a property in the master page and adding a directive in the

content page, now you can easily access the property in all the child pages

which inherit master page directive.

You can access this property like this:

Master.Section = "hello";