Amateur, Novice
noun
You've got a very elemental person. They're so elementary that they're quite an amateur, really. Maybe a little too elemental.
しろうと
Unfortunately, the reading for this is a complete exception, so you'll just have to memorize it. Here's a mnemonic to help you: "You're an amateur!", she wrote (しろうと). A little harsh, isn't it? But that's what she wrote. Gotta do a little better to impress her, pal.
やっぱりプロと素人は違うね！
Professionals and amateurs are indeed different!
なんか今の発言、素人っぽい。
What you just said somehow sounds amateurish.
ど素人の私でも出来たんだから、大丈夫だよ。
Even someone as wholly inexperienced as me could do it, so you'll be fine.