Web Sudoku Rules!

I mentioned yesterday that I'm like a Sudoku crack-head these days.
My Mother-in-law got me started and now I'm hooked. They are challenging/aggravating and once I start one I just mutter to myself till I either
A) finish it.
B) screw it up and toss it.
Yesterday I got this from someone named Jenngiglia(?)

Message: Hi Howard,
Try websudoku.com. You can play all levels and check with a "how am I doing?" as you go. Better than erasing over and over and tearing the newspaper.
J

Thank you Jenngiglia. Thank you for feeding my habit. Now I will get even less done.
If you like these puzzles this site is mother-lode.