![alt text](image URL)

I personally recommend the first one though, the second one I only use it because I'm far more used to HTML than to Markdown.

EDIT: ignore anything in "src" other than "image URL". All other stuff in that argument is an artifact of Neospring (another reason You should really stick to Markdown.)

EDIT 2: Ok, PCB, screw it: just ignore HTML and stick to Markdown next time! (Removed the second one)