Well, if I've grasped your question right, there are many methods to do that:
1)Response.Redirect > To navigate to another page from code and is equal to clicking a hyperlink. I suggest this as I think it's closer to your question.
2)Server.Transfer > This ends the current web form and begins a new web form. It's usable when you want to pass some variables i.e (Label1.Text) to the next immediate page. It's not safe though and not used to send passwords.
3)Server.Execute > This begins a new web form while the current web form is still displayed. Mostly used to combine web forms.
4)Window.Open > This is a script method and displays a page in a new browser window. As it is executed on the client, you can customize the appearance of the browser(i.e FullScreen) and though needs more coding.
I hope these cover your question.