If you don't care about losing the recording that you already have, then you can just plug the new hard drive in and unplug the old one. The only concern with hard drives (I think) is whether or not they're formatted correctly. The 1TB drive I'm using didn't require any special process.
With the new camera set up on your network, I believe all you need to do is go to the Setup - Add Camera page in the DNR-202L's direct IP interface, select the camera and enter the username and password.
If you would like the camera to send motion-detection events to the DNR-202L, then you'll need to set up motion detection in the camera's settings first, then turn on receipt of motion detection events in the DNR-202L's Setup - Event Setup page. (For recording motion detection events only, or for highlighting motion events on the continuous recorded stream.)