Well, I can't help you with a tanning trainer, but what I can suggest is you get out there with a bow and some arrows, and start hunting some game! Once you collect enough hides, you can take them to the tanning stations and transform them in to the leather materials you will need to start creating some of your own armor, if that is what you're looking for. Don't forget to see what other materials you need, and hunt them out! If there is a tanning trainer you should be able to find out their location on the wikia soon enough, if the information isn't already out there.