Puzzled Creator

Because I am a poor puzzler, I tend to enjoy creating puzzles (I think it's a sadistic streak).

Something funny happened though. I created this GREAT puzzle in Hong Kong (at least, I remember thinking it was great)... unfortunately, I never documented how to solve it since it "seemed so obvious."

Of course, now I don't remember how to solve it. The funny thing is that I know (roughly) what the solution is, but I don't remember how to get there.

Any puzzlers out there want to try this out, and let me know how to solve it?