Password form

Anybody can help me?
I have create a window app form using (microsoft visual C# express) which have one textbox only, for user to key in password. Below that I have put a OK button.
How to code so that when user key right password and click ok, user can go to another form and this form will close automaticlly. If wrong password also the form close automaticlly.
**What coding should put to textbox to take the user input and in the OK button how to evaluate the right and wrong password.
Tq very much.