Registration is a good thing. While Sync-O-Matic is shareware, it is good to be notified of new versions of the product. Sync-O-Matic does not have any code which contacts Sync-O-Matic Central notifying you of new versions. The good news is that once it is installed you don't get bugged all the time. The bad news is without registration, you will never know when a new version comes out.
Also, when people register, it lets the authors know that people care about the product. While money is always the best way to show that you care, registration is better than nothing. If the product is not used at all, then development will probably drop off to a crawl.
The fields are pretty self-explanatory. As you type in the registration code you get immediate feedback when a valid code has been entered.