From Oslo Airport Gardermoen, take the Airport Express Train to Oslo Central Station or Nationaltheateret Station (depending on the time of your arrival and the location of your accommodation). The journey takes approximately 20 minutes, and costs NOK 180.
The University of Oslo’s Blindern campus is located 3km north-west of the city centre, and is easily reached by metro (lines 4 or 5 westbound, get off at Blindern or Forskningsparken) or by tram (lines 17 or 18 direction Rikshospitalet, get off at Universitetet Blindern). Detailed info here: http://www.uio.no/english/about/maps/getting-to-uio/
The main venue for the conference is Sophus Bugges hus (the Sophus Bugge building), situated at the north end of the Blindern campus. The building is marked with a blinking green dot on this map: http://www.uio.no/om/finn-fram/omrader/blindern/bl05/
The venues for the workshops, the Museum of Cultural History and the National Museum – Architecture, are located in the city centre.