Learning Game

Hello, my name is Aaron Connelly. I'm currently developing an adaptable Flash language learning game, with sketches for some other learning games. I was wondering if it would be a good idea to make a website and place a prototype of the game on the site. Should I worry about someone "taking" my idea after I post it on a website or am I just being overly cautious? While I want to people to see it, I also want to market it when it is finished and I own a licensed version of Flash.

Thanks for your time.