The rules are simple. The numbers 1 through 9 should appear once and only once in each row, column, and each of the 3x3 sub-boxes. There is only one possible solution to each puzzle, and you are given enough clues to deduce the rest. This is completely logic based. There is no guesswork, meaning that if you feel the need to make a guess, you must be missing a clue somewhere. Keep searching, it is possible.

If you've got a browser that can handle css media types, then you can simply click print and you'll get what you want. If not, then there's no readily available solution, but most newer browsers support this. It's also fine to print with background colors enabled. Try it out.