I finally got another 2 TB SSD installed, now how do I use it properly?

Installed instore, registered well etc so all functional.

I want to transfer files from my C drive to it to free up space.

A little apprehensive as won't the links to games etc then say "root directory not found" or something?

Additionally, the computer wants to "copy" them over, then completely transfer them.

This is a rookie question but I just don't want to mess it up.

The other things is, games I have aren't really to be found in the "Program files" and "Program files x86" folders, but there's large files contained in Steam and Rockstar folders.

Do I move them over entirely or how does this work?

Steam has a function that allows you to transfer the installed files from one drive to another.