This is a small tip about ASP.Net. You might want to communicate frequently with your masterpage from a child page. For example, update current username in masterpage label control.
Suppose, you have an ASP.Net Label control in masterpage. ID of that control is lblUserName. You have an WebForm named Default.aspx.
Write this code in the code behind (i.e. Default.aspx.cs)
Label label = (Label)Master.FindControl(“lblUserName”);
if (label != null)
label.Text = “Welcome, ” + CurrentUser;