Hi George,

Me gustan means "I like them" or literally "they are pleasing to me." 

Hence me gustan las naranjas = I like oranges, or literally, the oranges they are pleasing to me. The formal (usted/ustedes) construction would be "le gusta(n) or les gusta(n) see below.  With gustar you use the different indirect objects to indicate to whom it is pleasing .... me, you, him/her, us, you (plural), or them, and the indirect object changes appropriately i.e. me, te, le, nos, os, les." 

There are a bunch of verbs that behave in this way and you will come across them in time. There is a lesson about the more common ones. If you enter "Gustar" in the search field next to your log-in icon at the top of the Dashboard page you will see a list of the various lessons available on this topic. The teachers may well add something to this reply.

¡Buena suerte! John