Dąbki. Look for connections to/from Koszalin. From Koszalin to Dąbki it is 29 km. You can use public transport (a lot of buses close to the train station) see example. You can order private car provided by organizers, just mail to PDF office (firstname.lastname@example.org). Price for private car Koszalin-Dąbki (one way) 60 zloty (up to 4 persons), or 90 zloty (up to 60 persons).
Koszalin. Trains in Poland see multilingual web. Koszalin is in the middle of the train line Szczecin-Gdańsk. You can also fight to Berlin. A lot of buses from Berliner airport to Szczecin, some of them even to Koszalin. See some examples like: Follow me, PKS Szczecin,
(1 euro = about 4,2 zloty)