Not all letters in the grid may be part of a word. Moreover, given that words can cross and overlap. Combined with the jumble of different orientations and positions, it may be extremely difficult to locate all of the words hidden in the puzzle.
One thing that makes a search like this more difficult is that many sites are either directories or attempting to sell a calendar program. The latter usually have something free to give away, but if they want you to buy a program the one they are giving away is pretty generic. Don't waste time trying to make the free one work if it isn't perfect on the surface. There are other choices that are completely free. You may have to try several options, but if you are patient and persistent you can find a truly free and printable calendar.