I know nothing of networking or anything of that nature Just 1 quick question. Is it even possible to make a normal computer game online? If so how difficult is it?

Do you have access to the source code?

If not, it will be at best near impossible and definately impossible in nearly every case.

If so, it depends on wether the rules of the game and/or the design of the game's code lend themselves to it. That will range from fairly simple to near impossible.

If you don't have the source, it's usually easier (less work, better result) to re-implement the game from scratch while designing the internals for networking. Assuming you already had the copyright holder's permission to re-make the game, that is.