Jeeze I learnt all that when I got my pilots licence but I can't remember how it all goes now...Doh!.

Basically you need to know the wind direction (heading) and speed, then use one of the many nav aid tools to work out what heading you require to stay on the correct track to get from point A to point B. Basically you end up pointing your nose in one direction (the heading) to allow for the wind blowing you of course while you plane is kind of flying sideways slightly on it's own heading (Track). Then as you turn your next course on your flight plan you change it all again.

I have a little whiz wheel that would help you work all that out, it's just been an age since I used it.

also maps use to show magnetic declination for a given year and give a number to add every year from it to calculate the course

many thanks to Robo. for the explanation on the compass.
after reading the tf wiki and the game manual, (and finding nothing,) I was starting to loose hope...