Where to play flight simulator online

You can join the on line flight community of GAMESPY which is accessible through the Flight sim programme
You can also join one of the 3 flight simulation networks at NO COST
They are Virtual Skies, Vatsim and IVAO
Each offers something of the same - but there are opportunities in all not just to fly but to be trained by their in-house trainers as a Air Traffic Controller with their own free software which they allow you to use. This will let you control real people who fly virtual aircraft on their network