From the airport you have to take the bus 200 to the end (Köbánya Kispest) and from there take the metro to Corvin negyed, from here take the tram 4or 6 to Harminckettesek tere .
From the bus station ' Népliget' just take the metro to corvin negyed and the tram 4 or 6 to Harminckettesek tere.
From train station Keleti: Take the Bus 7 to Blaha Lujza ter, then the tram 4or 6 to Harminckettesek tere.