I'm working on wordpress and I want to order my post by rating. I'm new with it, and I need some help. I tried many things, but seem it's not working :/

My Wordpress Custom field which contain the numerical value (rating) is : geekmag_cmb2_general_review

I have heard about WP Query but don't understand how it works/use it and where should I write the WP_Query :(

Sorry if it seam easy to you, but I really want to understand how to do and how it works, that is why i post here.

Here image about how i can filter right now

Thank you !