Hey guys

New to programming completely, but been reading some books and having a muck around on VB 10 Express.

Im in the process of creating a keypad which I can punch in numbers 1- 9 to enter a password. I have 9 buttons for the numbers. I've got the keys to print the numbers into the textbox above but when I press a second key it replaces the first number in the text box.

My question is, how do I make the numbers go in sequence, so instead of

(Press 1) - 1 -
(Press 2) - 2 - (clears 1)

I want it to go like

(Press 1) - 1 -
(Press 2) - 12 -
and so on...

Coulden't find this anywhere else.
Cheers guys!