Hello!
I'm quite new here as well, but got the mods working fine yesterday.
All you have to do is find the steam nr's attached to the mods. Quickest way is going to the steam using your browser (not the program).
https://steamcommunity.com/workshop/browse/?appid=244850
Search for the mods you like and copy, paste the number into the Nitrado list (see my attachment). Look really well if you have coppied correctly since I got a few doubles yesterday. Extra tip first make the list in notepad.
Paste the number? What number... this one within a mod URL: https://steamcommunity.com/sharedfiles/filedetails/?id=1978031017&searchtext=
Good Luck!