Step 11: Priming
Congratulations, you now have beer! But, you're not done. If you drink it now it's going to be flat. Priming is the process of adding a measured amount of additional fermentable sugars just before bottling. Live yeast still in your beer will convert the additional sugars to carbon dioxide while in the bottle. The carbon dioxide has no way to escape the bottle resulting in carbonated beer.
Boil 3/8 cup (1/4 cup plus 2 tablespoons) of sugar (preferably corn sugar but table sugar will do) in 1 cup of water for 5 minutes. Cover and let it cool some then pour into a sanitized container large enough to hold your beer (another large empty water bottle, empty plastic bucket, etc). Now siphon your beer from the fermenter into the bottling container being careful not to disturb too much sediment at the bottom of the fermenter (you did remember to sanitize that siphon hose, didn't you?). Your beer is now primed and ready for bottling.