Okay, you know how an engine works...
A Jet engine, sucks air (alot of it) some of it, (about 20%) is sent through a compresser to increase the pressure and then is burnt, increasing the pressure further, then sent through a turbine to keep it spinning. Then it is exhausted out the back. about 80% of the air is not sent through this combustion process and bypasses around the outside of the core.
This is called a High Bypass Ratio Turbofan engine this type of engine is reasonably quiet compared to a turbojet it is also VERY fuel efficient.
If you send most of the air sucked in through the combustion process then it is called a Turbojet. These engines are very loud and not very fuel efficient.
A Turbo Prop is a prop that uses the same combustion process of a Turbofan to keep the prop spinning (compressor, combustion, turbine) instead of an ordinary prop which uses pistons.
Its not a very good description but should help you out till someone else gets here