Coat the bottom of the tagine with oil. Vegetable oil works well, but any kind of oil that can deal with heat should be fine.
Pick out whatever raw ingredients you want. Veggies always work pretty well. If you want to be traditional, definitely pick up some potatoes. If you want to experiment, you can even throw in some fruit. I strongly recommend adding tomatoes – their juices seep into everything in a tasty way.
Cut your veggies and such into bite-sized pieces.
Throw your raw ingredients in the tagine. Pour in a little water and oil. Then put the cover on and put the tagine over low heat.
Let everything cook for 45 minutes, stirring every 15 minutes. Cook until the mixture ends up like stew. Then, flavor it. Experiment with different spices, oils, salts, sugars, vinegars...
That's it! Oh, and don't go near your tagine with a fork. Instead, use pieces of flatbread to pick up the food with your hands. Bon appetit!