You can download an example booklet with four problems: Two easy ones, one intermediate, and one hard problem. Or, if you like X-Sudokus, just download a booklet with X-Sudokus also with two easy, one intermediate, and one hard problem. To view or print this example you need the Acrobat Reader (available here).
And to start immediately: Just download a bunch of already generated problems.
And to start immediately: Just download a bunch of already generated problems.