VB.NET 2005 - need help with recognising colours!

Question

hi, i am trying to make a pacman style game on VB 2005, and basically i am stuck on making the pacman to not go through the walls, i know that i need to get it to lyke recognise that if a person presses the key to go forward (or whatever) the code needs 2 check to see what is in front of it colour wise, so if its blue pacman won't go forwards but if its black it will, can anybody help plz? ty