What is that person’s name?
I've heard the name, but I don't know much about it.
I want to change my first name to "Ah" and my last name to "Soso."
Your name that's in the front. That is not your last name, that is your regular name or your first name.
This word uses both kun'yomi readings (oh darn!). That being said, you've seen the kun'yomi readings for both the kanji that make up this word. The word 名 (な) and the word 前 (まえ) both are kun'yomi, so use those words and Voltron them into a single word, なまえ.