I'm a layman. What I'm going to say may expose myself to ridicule, yet I still want to say a few words.

我是个外行，我说的话可能贻笑大方，可我还是要说几句。

《新英汉大辞典》

Sorry, I'm a layman in that area.

很抱歉，这方面我可是门外汉。

youdao

Well, I have heard something about it but I can't say that it is very clear to me. I must admit I'm a layman as far as insurance is concerned.

mm哦，英语四级考试据说过一些，但四级考试不能说很明白。四级考试得否认，就保险而言，英语四级考试是个外行。

youdao

I'm just a layman in making that observation, but I think it's true.

WHITEHOUSE: Press Briefing