How to correctly add your “input” field to the forum (reviews) on the CMS 1c Bitrix website?

Question

1C-Bitrix

There is a site on Bitrix, on it there is a template from "Aspro" - Tires and wheels 2.0, product reviews on it are implemented using the Bitrix forums service.
We have a feedback input field and the ability to attach a file (image).
But this is not enough, you need to add the "Advantages" and "Disadvantages" fields and, accordingly, after filling in, these additions should be included in the review. The scheme is simple and is used in almost all major online stores.
Why not install a ready-made solution, you say, there are two reasons.
Firstly: The BUS license has expired...
Secondly: The standard solution will be enough for me if it is finalized (in my opinion, a little).
Well, since I'm a lamer.) I need at least advice on where to dig and where exactly you need to insert the input field, as well as how to do it correctly ... Surely there is some other handler that also needs to be edited ...
Internet search Unfortunately it didn't work...