I am a complete newb, though I want nothing more than to be able to program at a bare metal level and help develop for this platform. How do I get started?

I am sure there is likely many emails like this, and I have truly done my best hunting for information. I have a small understanding of assembly, and have tried reading TRMs to no avail. Is there any texts anyone could recommend to get me started?

I would truly be ever so grateful for any advice.