There are many ways. I have a 8ft by 3ft above ground pen that will house 24-25 birds. If I may offer a word of advice the best thing to do is get a book on raising and breeding gamebirds...and also join a gamebird forum. Thats So Quail Place is a great forum.
Click the link in my sig, follow the links to the pheasant page - there are images for nearly every species (same for most quail and other wild galliformes). Sam gave some good advice with checking out a book - check out authors Delacour, Johnsgard, Madge, etc. Also listed on each of the pheasant pages. You will see that size and aviary type does vary for each species.