Local transport in Bochum is operated by Bogestra. You can buy their tickets at the ticket machines around the station; it is much easier if you use red Bogestra ticket machines as opposed to green machines that sell regional train tickets as well. At the main station red Bogestra machines are in some abundance on a floor just below the main entrance (take the stairs/escalator opposite of the main departures tableau)
Your ticket options include Single Ticket (Einzel Ticket erw.), 4-Ticket (4-er Ticket erw.) or 24-hout ticket (24-StundenTicket). Price-wise buying 4-ticket or 24-hour ticket (Zone A) is better.
Note that you have to validate every ticket by stamping it in a red box inside the transport (24-hour ticket has to be validated only once).
If you are confused about zones, buying tickets in Bochum means Zone A covers all transport within Bochum (Zones B and C are for traveling longer distances).
To get to the university take Campus Linie U35 in the direction of Querenburg/Hustadt (on the platform the tableau will list the final stop instead of the direction; in this case typically Hustadt). Exit at Bochum Ruhr-Universität.
In the opposite direction take U35 in the direction Herne (the tableau will typically list it as Riemke Markt or Herne Schloß Strünkede). Exit at Bochum Hbf.
(you can click on the picture to open a zoomable version)
1. Immediately after crossing the bridge towards university take a turn left. You will see a building labelled SSC (pic 2).
2. Take the stairs (left arrow in pic 2) or the elevator (right arrow) one floor down.
3. Turn the corner on the building you're next to and proceed straight.
4. You will see the building labelled IA. Enter the entrance as in pic 3.
5. You are on the floor E02 which is not to be confused with the floor E2: zeros are used to denote the floors lower than floor 1 (don't ask, I know).
6. Walk straight until you see a set of stairs on your left (no doors) and take it one floor down to E03. Then simply proceed straight for quite some time until you see *SIGNS*: you will need to cross buildings IA to IC before you reach the required ID. The room is 03/653.
7. Alternatively, you can take an elevator to get to E03 but keep in mind that you cannot take the first set of elevators: it is a dead end. Walk straight until you reach IB and take an elevator there (again, to the floor labelled 03 in the elevator).