Firstly, - do as Greg has mentioned.
Then you need to figure out if the username and password is correct or not. For this you will need to access your Database, and query for the user entered username and password. I cannot give you any more detail here before you mention what technology you will be using for DB access.
Another thing is you mention calling getPassword and printing on the screen. This is not a done thing in any app - ever!
for the final step you have mentioned you just need a loop that would return when login is successful. Something like this (note I have not used your KeyboardReader class as that must be a proprietary thing you are using)