What is automatic writing?
Automatic writing is when you produce written words that you didn't form consciously. It's a form of channelling where you bring through the information and answers from the spirit world, or in this case, from your angels. You become their tool and you usually have no knowledge of what've you've written until you look at it afterwards.
How do you do it?
When you've finished, look at what has been written and see if you can discern a message there. But remember like any new challenge it may take a few attempts before you achieve success so don't be disheartened if at first you appear not to receive any messages of relevance. As the saying goes 'practice makes perfect'