The most convenient ways to reach the Centre are by taxis or buses.
From Poznań Ławica Airport to the Centre:
Bus 59, 48 or Night Bus 242

more information:
https://www.airport-poznan.com.pl
http://www.poznan.pl/mim/komunikacja/en

Dworcowa 1, 61-801 Poznań

In Poznań:
Public transports are very convenient inside Poznań either by trams or buses.
Information can be found at: http://www.poznan.pl/mim/komunikacja/en