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
_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.