Really easy question, How to set a background image?

Okay, its been a while since i last used this software and because i’ve been so busy modelling in 3Ds Max I have totally forgotten everything lol!

All i want to do is set an image as a background, as im making an arcade style game

Thanks in advance!

=]

This particular question has been asked several times and there are a few ways of doing it, here is one that has been posted already that is widely used: