There are a few tutorials in the docs too, such as the More[1] tutorial. I agree that it could be nice to have "Racket for X programmers" guides.
If you get stuck, the community on IRC at #racket on Freenode is friendly & active and so is the mailing list.
Call a plumber and the faucet starts working.
But the question still stands, where would you point and experienced C-side programmer to start off in racket?