Ok, you need something to burn to start the process. This will later be replaced with the product, but to get started you need a fuel source.
We start by removing the water. Traditionally, this was done in a very inefficent manner, such that the total efficiency of removing the water took more energy than the product produced. Now, we use water to our advantage. Start by sealing the container, and heating it to ~400 F, and about 350psi. This breaks down the carbon strings a bit. Now, remove the pressure and you will remove most of the water - which we reclaim for heating the next batch.
This hot mixture (now minus the water content) is heated to about 600 F, under about 400 psi (much lower pressure/temp ratio, as the water is gone). Let sit for about 2 hours. This really breaks down the hydrocarbon stings. By the way, this is EXACTLY how we make gasoline and ligher petrolium oils.
In short, we have done in a matter of hours what mother nature takes millions of years to do. Pressure and temperature transform a forest into coal, dinosaurs into oil. We just sped the process up a few billion-fold.