How can I find user information in asp .net?

How can I find user information in asp .net? I have a web application where I am supposed to display user information on the landing page once they sign in. I managed to do so. I also have an option to 'Find User' - once the user inputs a username to find and clicks on the button, it should display that user's information. However, I keep getting the information for the user that is logged in.