A balancer is a separate unit that you would connect to the balance lead of the lipo. There are different types of balancers. Some balance by discharging specific cells to balance out the pack. Some balance by regulating charging voltage to specific cells. Some give you an option to do either. like this one;
http://www.amainhobbies.com/product_...ducts_id/23940
You can simply plug the banana plugs into your lipo charger and plug the other end to the balance lead of the lipo and start charging.
Some chargers have built in balance charging capabilities and you wouldn't need a separate balancer.