This is for all the people who cannot find information about public transportation from Colmar to Freiburg, Germany, on the Internet.
Go to the tourist bureau or information center, and get a bus schedule for Freiburg. The bus driver will sell you a ticket for the bus and for the train connection when you board the bus.
The bus will take you, eventually, after stopping in a few small villages, to Breisach, Germany. Here, you get off the bus and walk straight ahead, literally twenty feet, and get on the train that will probably be waiting for you (The French and the Germans have coordinated this pretty well.) No need to stamp your ticket first. Just have it ready in case the conductor asks.
There are several stops in Freiburg. It's the third one that lands you in the center of town.