A Turbojet works by sucking cold air in from the inducer (or inlet) which is then compressed by the compressor in the compressor housing and flows through the cold-air duct into the combustion chamber where it is mixed with fuel (propane in this case) and ignited with a spark plug. 
The flame tube in the combustion chamber holds the fame and allows the high pressure air to flow around it while mixing a small amount of that air with the fuel and preventing the flame from actually touching the walls of the combustion chamber. 
Next The hot exhaust gasses from the combustion process flow  through an elbow into the turbine housing, thus turning the turbine.
Since the compressor wheel and turbine are fixed to the same shaft, when the exhaust gasses turn the turbine, they also turn the compressor wheel, pulling more air into the combustion chamber for the combustion process, creating a continuous cycle.
This is why turbojets usually need an external force to turn the compressor wheel to start (ie leaf blower, electric motor, compressed air etc). Simple turbojets like this are not as efficient as turbofan engines (used on most jet powered airplanes). Maybe I'll build a turbofan next...