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 have to remember the まな part to learn this word's reading. Think about a class you're taking. It's a manners class, and you're there to learn manners (まな). Imagine this study of manners and imagine yourself practicing it.
I’m learning Japanese through self-study.
Why don't you learn how to make weird faces and poses with Tofugu, instead of studying Japanese?
Learning is important, but perhaps what’s more important is how you learn.