So if you want to find cdp files from jointedrail or wig wag simulations, what I prefer, your choice, search like on Google for trainz mod sites, typically what I do :)

So you have your cdp file ready?, so you should open "manage content", which is the 3rd option of the t:ane or trs 22 game launcher,

1) go to file
2) import content files
3) select the cdp file, then press open
4) wait, then done!

Alternatively you can just do:

1) go to file
2) go to import content files
3) drag your cdp file or files, how many you downloaded, and done!

Understand now?