In TS2022 modding covers a wide variety of activities and. As I see it there are four types of modding: Creating or altering routes and scenarios using the built-in functionality of TS2022. Start by going to the Manuals folder and reading the manuals provided by DTG (RW Creator Manual and RW Timetable View Manual). There are also a lot of Youtube videos by various people to guide you. In my installation the English language manuals are in D:\Program Files (x86)\Steam\steamapps\common\RailWorks\Manuals\EN Commercial enhancement products. (e.g. RW Enhancer, Armstrong Powerhouse weather pack, etc.) Follow the instructions that come with them. Third party stock, reskins etc. Follow the instructions that come with them. Creating your own models. Complicated and takes a lot of time to learn. I haven't done this, so can't help you.
Some of the mods come as a .rwp file and you use Utilities.exe in you Railworks Folder to install the fies Tell us what the mods are and we can help. Peter