する verb
さんかする
今週の日曜日、摩天楼の見学ツアーに参加します。
I’m participating in the skyscraper observation tour this Sunday.
You know how 参加 is participation? Well, make that a verb with する and you have yourself to participate.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. Will also help to know the reading of 参加.