I'll follow your example and then give a bit of an explanation...
Color : Green or Blue
Material : Paper
Screen Size : 6' paper is fine for head shots, you can go longer
though
Where to buy: Any good photography store
What you want is the ability to key out the background and that is what green or blue paper gives you. It's fairly low cost and not all that hard to do. Big things to remember if you want to knock out the background is:
Even lighting.
Avoid shadows on the paper.
Keep the subject far enough away so as to avoid having the background reflect on them.
Make sure your subject isn't wearing the same color. A little easier with two colors to choose from, though you're toast if they wear both... :D
I suggest paper because it's relatively low cost, you can discard the dirty portions, and it's easier to keep smooth and even.
The term you want to search for here and at Google (or your search engine of choice) is "chroma key."