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 decide to add something and then to add something else, and you end up with quite a quantity (くわ) of things. Just keep adding and adding forever. What a huge QUANTITY you now have!
Please add two cups of milk and stir slowly.
Can you include Koichi-kun in your group too?
I added a pinch of salt to the dish President Obama made.