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:
Everything in your room has finally been put in order. Just as you finish, you hear a crash and turn to see your dog has jumped up onto your desk. "Toto no (ととの)!" you yell as he knocks everything over. Guess you have to arrange it all over again. Dammit Toto.
Viet arranges his mustache into a triangle every morning.
My older brother put all the things in order regarding our father's funeral.
We’ll introduce you to methods for getting your hormone balance in order.