By giving it the malt to snack on in the fermenter, you re fermenting the beer. By giving it the priming sugar to snack on in the bottle, you re carbonating it. It is important to use high quality, fresh yeast. You can t use bread yeast. They re very different.
Brewing yeast comes in several forms.
The most common are liquid, and dry. Using liquid yeast is a little more involved, and beginners generally start with dry yeast. Liquid yeast is also more expensive. Intermediate and advanced brewers will use liquid. To use dry yeast you simply pour the yeast into about cup of warm water and let it sit for 5-10 minutes.