See also, How to Eat Mexican Chocolate and Fear the Swiss
Step 1: Materials
If you have a brick of chocolate, use that. You can buy this stuff in stores under brands like "Ibarra" and "Abuelita". If you use the store-bought stuff, don't add any sugar.
Step 2: Melt the Choclate
Add a little milk.
Let the chocolate get warm and liquid.
Step 3: Add Milk
The chocolatey-ness of the final beverage is inversely proportional to the amount of milk you add.
Step 4: Add Spices
If you care to, you can also add nutmeg, orange peel, or anything else you enjoy (red pepper, dark chocolate flakes, I don't know - throw stuff in and see if it tastes good)
Step 5: Warm
Step 6: Blend
This will cause the beverage to be foamy and delicious.
If you like having chunks of chocolate at the bottom, you might be able to save some from your saucepan, and add them in, after blending.