RECOMMENDED READING LIST
So you want a little background information eh? A little theory? Well, that's all well and good, but here are some books that will give you a little bit of that and A LOT OF GOOD STUFF TO DO IN THE CLASSROOM!
First of all I recommend the title PRACTICAL ENGLISH USAGE by Michael Swan, Oxford University Press. This is a veritable bible for teachers around the world, and is probably the best general grammar reference you can get. It'll give you more confidence when faced with annoyingly grammar-minded students, but remember, never admit you don't know something. Just stall them til you can look it up.
Two good books by all-round English teaching specialist Jeffery Harmer are THE PRACTICE OF LANGUAGE TEACHING and HOW TO TEACH ENGLISH. These are popular books for training courses, and with good reason -- they cover all the basics. Nothing that's going to help you too much in the classroom, probably, but a good place to start.
Now if you're interested in what you should actually DO in class, rather than just what the theories are, check out the ENGLISH FILE text book series by Clive Oxenden and Paul Seligson (with Christina Latham Koenig). The teachers books offer some INVALUABLE examples of skeletal lesson plans, especially at the beginner levels, and the books themselves are right up the minute, theoretically speaking, if not topically. There are also SHITLOADS of useful games and exercises and activities in the back, ready for photocopying, far better than any of those dumb PLAY GAMES WITH ENGLISH things.
I feel that while there's a lot of rather goofy stuff in the books GRAMMAR PRACTICE ACTIVITIES by Penny Ur and FIVE MINUTE ACTIVITIES by Penny Ur and Andrew Wright, they will give you a lot of good ideas on the different ways you can adapt different activities into games, and a lot of the stuff ain't bad.