Again, just like the others. TWO ways to go about this!
The Long Way:-Start career with Mclaren, Alfa Romeo or the big three, race to your hearts content until one of these teams offer you a contract and simply accept to unlock!
The Short Way:-Start Career mode, on the F2 races simply crash out or retire to get to the agents office quickly at the end of the season, accept one of these teams offers (Crashing out of those F2 races has no effect) and voila, achievement unlock!