You must register (matriculate) in writing: forms are available from the 'Universitätskanzlei' or at any 'Mittelschule'.
Either a Maturitätszeugnis or a recognized equivalent is required. The corresponding documents must be presented at the 'Universitätskanzlei' at the very latest on the first day of your course.
It is recommended that students begin their degree course at the start of the academic year (October).
You can register for the winter semester at any time before it begins. Registration later than June 1st usually incurs an administrative fee.