I like decorating the Christmas tree. I put it beside our fireplace this year.
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means decorate. The verb vocab version is to decorate.
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: To decorate something, you don't really need a cause (かざ). You should just do it, just because.