Since this word is made up of a single kanji, it should use the kun'yomi reading. You haven't learned this reading yet, so here's a mnemonic to help you remember:
Picture your older sister (even if you don't have one), her birthday is coming up and there's only one thing she wants from you. A necklace (あね). She's wanted a necklace for years and you're finally going to give her one. She'll be so happy.
I’m just about to go to my older sister’s house.
I have five times as many books as my older sister does.
My big sister works as a stewardess.