The kanji itself means participate, so you'd think this word would mean "to participate" but it doesn't (sorry!). It's a little more complex. Think of it as "to participate" but where you have to come or to go in order to do it. This is the humble way to say those things, so you're going to these places with your tail between your legs, just happy you can participate more than anything.

Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you: You get to come to participate! "It's my (まい) lucky day!" you exclaim.