By train ...
on the InterCity train station Freiburg (FR), change to the local train to Hinterzarten (direction Titisee-Neustadt, runs every half hour) from Munich (via Ulm) drives 1x daily a direct Regionalexpress over Stuttgart and Ulm, Donaueschingen, Titisee-Neustadt (change) to Hinterzarten (Regional). More information on train connections can be found at: www.bahn.de

By plane ...
via Zurich (approx. 1.5 hrs transfer)
via Basel (1 hour transfer)

By car ...
on the A5 to the exit Freiburg-Mitte, crossing the French border near Breisach, and then to the B31 direction Titisee-Neustadt Donaueschingen Hinterzarten.
Or: Take the A6 towards Heilbronn and / or the A8/A81 towards Stuttgart and Singen, at Dreieck Bad Durrheim go direction Donaueschingen, then on the B31 towards Freiburg Hinterzarten.