The only way to know for sure if it is done is to take hydrometer readings for a few consecutive days. If they all read the same, fermentation has completed.
What to do at that point is up for friendly debate. Some say leave it in the primary to let the yeast continue to clean up, some say transfer to a secondary to clear, and some bottle. Depends a lot on how much you want to chance infecting or aerating the beer, and how bad you want to drink one will dicate your next move.
Get a hydrometer...It's the only way to accurately know when ferm is complete...
I thought I'd give you some links to some threads that will help you with your beers. They will have a lot of info that will answer most all your questions and ease any worries you might have...Starting out.