formsauthentication remember me checkbox

Hi i have the following code which log in a user, i also have a "remember me" checkbox, how do i implement it into my code to ensure it remembers the user, here is my code;
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["SportansConnectionString"].ConnectionString);

string UserPassword = FormsAuthentication.HashPasswordForStoringInConfigFile
("PFAGJSK" + txtPassword.Text.ToLower(), "SHA1");
SqlCommand command = new SqlCommand("User_login", conn);
command.Parameters.Add("@UserName", SqlDbType.VarChar).Value = txtUsername.Text;
command.Parameters.Add("@Password", Sq ...