If you mean a white background, there's numerous threads in the lighting section, but the starting point is a flash either side pointing at the opposite side of the background and overexposing by less than a stop (try 1/2 a stop and see how you get on).
Of course there are many other lighting techniques for backgrounds - so if it's not plain white, give us some more detail and I'm sure you'll get a comprehensive answer.
You might be better asking for this to be moved to the studio / lighting section, where it'll be more easily spotted by the lighting experts.