The nearest airport is Paderborn/Lippstadt Airport (airport code: PAD). You can use a taxi - total journey time 30 minutes, approx. 35 Euro.
Alternatively you can take the express line bus S60 (journey time: 20 minutes) or bus No. 460 (journey time: 30 minutes) towards main station "Paderborn Hauptbahnhof". One way ticket for 6,60 EUR. The Bus stop is in front of the Arrival Terminal. Please see the time table.
From the main station you can take a bus or a taxi (please see: how to reach us by train).
The main alternative airport is Düsseldorf (airport code: DUS), which is connected to Paderborn main station at least once an hour, the ride is about 2 hours 10 minutes, sometimes with the need to connect in Hamm, sometimes with direct trains. Other airports (Hannover HAJ, Dortmund DTM, or Cologne CGN) are considerably less convenient.