Such prudes on this site. There is nothing wrong with starting something with a younger man. There is nothing wrong with meeting people at your kids activities (single parents don't get that much time to socialize apart from their kids). The other single parents at these events are your peers. If you want it, there is nothing wrong with going for it.
Flirting is pretty easy for women... you start by talking with him, laughing at his jokes. You can ramp it up by either touching him on the shoulder, or making coy suggestions. If you want to be direct... simply ask him "hey, would you like to have coffee sometime".
Of course, there is no guarantee that he will respond, but there is nothing wrong with trying. And you might get a relationship (and good sex) out of the deal.