The address of the building of the School of Business and Governance of Tallinn University of Technology is Akadeemia tee 3, Tallinn.
You can get there from the city centre using public transport. Take bus number 83 (route Mustamäe-Kaubamaja) from the terminus Kaubamaja or from bus stops Vabaduse väljak or Koidu (e.g. if you are staying at Kreutzwald Hotel). You need to go in the direction of Mustamäe and get off at the bus stop Keemia (it's an approximately 25-minute ride from Kaubamaja). When you have got off the bus, walk back a bit and cross the street (Akadeemia St.) at the zebra crossing to get to the bus stop on the other side of the street. The building is practically next to the bus stop (to the left of the bus stop if you are facing it). It says Taltech School of Business and Governance on the wall of the building. The main entrance faces the street. Enter the building, turn right, take the stairs or lift to the second floor and you have reached the lobby. Classroom SOC-211A and SOC-211B are there too. There will naturally be signs to direct you.