Short term and long term memory. converting and such.

[Theory5]

Hello all. I havent posted in a little while but today my reading teacher attempted to tell our class about short and long term memory. It wasn't a very good explanation,and it was simple, and it really didn't help.
Now I really don't read much about the brain, but I know I did read an article about memory or something that had a brief summary of how memory works. Your memory consists of these structures or something, that hold memory in them. i think at the interception of the long tube things. I don't really remember. Could someone tell me about long and short term memory and how it is converted?
Also, she said that it is impossible to forget something once you learn it(i think there was her mistake, she said once you learn it, not "once you convert it into long term memory" that stumped most of the class unfortunatly. (I go to a vocational technical school and I think i was moved into a lower reading class (but with the same teacher) when they changed my math class.)) anyways please inform me about this.