I don't know any online resources but while I was in the SAF MDC, I had to play some jazz.
The thing is, I never go into it. It still doesn't connect with me.
Hence, after the months of jamming/practicing/trying, I can only boost of doing some lame imitation of jazz.
So one aspect you should and MUST start out, if you want to learn a particular genre of music, is to listen to it.
Check out some classic dudes like Chick Corea, Duke Ellington, Joe Pass, Pat Methenay and so on.
There's nothing to be afriad of when it comes to jazz, sure it has "more" theory and "more" stuff to learn, but hell, ask a jazz guitarist to play some headbanging thrash metal riff/licks. Chances are, he'll be like me, just imitating to the best of his abilities. He'll never be as thrash metal as the REAL thrash metal guitarists. Have passion, will travel. Just go for it.