Learn them and slowly you'll be able to reconize and figure out when to use them. Start with something simple as the singleton pattern :)
if you want to create one instance of an object and just ONE. You use the singleton pattern. Let's say you're making a program with an options object. You don't want several of those, that would be silly. Singleton makes sure that there will never be more than one. Singleton pattern is simple, used a lot, and really effective.