If you mean after you meet Kavar in the cantina, then you go back to your ship. If Onderon is your last planet, you will get a message to go back to the Mandolorian camp. If it's not your last planet, you need to beat one more planet then you're allowed to return.
or if you havent got onto onderon yet, then the you need to help out the mandalorians around their base so that Mandalore takes you to onderon in his shuttle