Seebronn is part of the Swabian city of Rottenburg am Neckar. It's located approx. 40 kilometres south of Stuttgart and close to motorway A81 at exit Rottenburg (no. 29). From the exit on, follow the road signs to the venue, the camping site and the parking lot.
Here's an OpenStreetMap with the location of Seebronn:
Approach with public transport
Closest major train station to Seebronn is Stuttgart. From Stuttgart you'll have to take the regional train to Bondorf or Rottenburg-Ergenzingen. For detailed connection schedules consult the site of the German train company www.bahn.de, please.
There are bus lines from both Rottenburg-Ergenzingen and Bondorf to Seebronn. The site www.naldo.de will provide with the according running schedules.