Re: how does a rocket engine work?

There are different types of rockets, but basically rocket fuel is burned and 
exhausted out one end of the rocket with enough force to lift the rocket.

There is a lot more to rockets than you can find on the internet.  The 
following are some of the sites available:

Design and build your own:

http://www.im.lcs.mit.edu/rocket/

How model rockets work:

http://www.rockets-2-go.com/ur001.htm

Historical data on larger rockets:

http://www.asi.org/adb/04/03/09/01/index.html

Thanks for your question.