So how then did you learn?
Dont tell me its the families native language!
lol, my wife would say it's my second language!
When I first started with Amibroker TJ was putting out a "tips" newsletter up until around 2002. They're still in the Amibroker members area, a bit outdated now but still worth a look.
There's also AFL's published in S&C magazine and posted in the members area each month. There's the equivalent Metastock version as well which may help in your coding some of your Metastock stuff into AFL.
The AFL library has a good collection and working through the indicator/system/exploration etc. examples there gives a good insight into how Amibroker array processing works.
There's a good collection of AFL's on this site now too:
http://www.wisestocktrader.com/indicators
You already understand system development etc. so you'll pick things up a lot quicker than most and you'll be able to spot the crap and ignore it quicker than others too. Unfortunately it's like everything else, there's really no shortcuts... 10,000 hours
Oh, I should add that there's plenty of written and video tutorials on the support page:
http://www.amibroker.com/support.html
The Amibroker Yahoo group is a must to join too:
http://finance.groups.yahoo.com/group/amibroker/
Set it to send you each post via email, much easier to sort through that way.