You don't need to use the linking function, since you haven't played on the main site before. If you want to play Elements on the main site without losing any of your progress made on Kong, then the following should work:
Log in to Elements through Kong, then check your Account Info in-game.
Check your username and password; change your password if you need to.
Load up Elements on the main site, then enter in your username and password that you got from the Account Info screen into the Login screen.
You should have all your progress from Kong when you play Elements on the main site.