I want to display the username of Login Page on to the respected redirect page after successful login.

After Validating the Username Before redirecting to another Page keep username in Context

i.e Context.Items.Add("UserName","YOur User Name");

Replace Your User Name With txtUsername.Text.

In Redirected Page

In !isPostBack

lblUserName.text=Context.Items["UserName"].toString();

Read and explore: Page and Application Context in ASP.NET Web Applications[^]

Use Session[^]
Try this:

In login page after validation

Session["Username"]= txt_username.Text;
//redirect url

In Homepage/RedirectedPage:

Label1.Text = Session["Username"].ToString();

After successfull login u can store the user name in a session variable as below

Session["username"] = txtUser.Text;

and in the master page place a label and assign text to label as

lblUser.Text = Session["username"].ToString();