The password textbox needs to have the PasswordChar property set to '*'.
In the General/Declarations section of the code window, you will need to declare an Integer variable, which will count how many attempts the user has made. When the user clicks on the OK button, the code will check to see if the correct password has been entered. If not, the value of the Var1 variable will be incremented by 1. If the user enters three incorrect passwords, a message box will appear saying that the program will terminate, which it does afterwards.