For Login read some to understand

string username = "SwitchBlade";
        string password = "Leavl 7";

On Top of public Form1() do



if(usertxt.Text == username)
            {
                if(passtxt.Text == password)
                {
                   Form2 tampil = new Form2();
            tampil.Show();
            Visible = false;
                } else
                {
                    MessageBox.Show("Username/Password Is Incorrect!");
                }
            }
        }