Since May 21st, 2013, you can register for your exams. This is done in the QIS.

You have three weeks to decide, which exams you want to take this semester. The registration period for first registrations for bachelor students expired on May 29th, 2013. Students registering for their first master exams, as well as all other students, can do that until June 11th, 2013. A complete list of the registration periods and other dates within the semester can be looked up here.

For oral exams you have to register in the examination office (Prüfungsamt). Printed forms are available there, on the Fachschafts-pinnboard near room 48-452 and online.