You will find all important information here.
Lines to the airport: S8 and S9 in the direction of Wiesbaden/Frankfurt Flughafen, the ride will take approx. 15 min. The S-Trains you will find in the central station. You will take the escalator downward located next to McDonalds. The arrival will be at Terminal 1.
To get to Terminal 2 you can either take a free bus located at the exit or the free overland railway located in the airport.