How to program a textbox to only accept integar numbers in VISUAL BASIC language

I am trying to code a moving square project for class, in which i have a textbox and whatever number i put in a box my squares have to move that many loops and I think i got it down that far but i also have to make sure that when i put a non integar number i get an error, CAN ANYONE PLEASE HELP ME WITH THAT?

IF IT IS ALSO POSSIBLE, CAN YOU PLEASE WRITE A CODE FOR ME.

THANK YOU!