Where to go to learn how to fix my mercedes

I want to become my own mechanic
I'd like to be able to repair or fix almost *anything* relating to my Merc

I've never done anything relating to the car!
Though... I'm very hands on with everything and not afraid to get hands dirty

Can someone tell me where to start...?
Are there any video guides anywhere?

OK... so there's mechanical - do I have to learn any theories or do some sort of book work before or during opening bits up?

Then there's the electrics - is this a separate discipline?

Then we have diagnostics - this is what really interests me... where do I start with this?

Thanks


OM