There are two standard containers that beer is put into when it is done in the fermenter. It is normally put in a Keg or Bottles/cans. The kegs are normally made of stainless steel, and sometimes aluminum. With the kegs, they need to be fully cleaned first. Once they have been fully cleaned and dis-infected they are filled with the beverage of choice, normally beer. The lid is placed on the keg, and the keg is pressurized with CO2 to carbonate the beer. After a week of roughly sitting with the CO2, the beverage should be carbonated.
With Bottles though, it is a different story since they are unable to use CO2 to pressurize them. The yeast does the work by the extra sugar added in before bottling.