Q: using ipad calendar, how do i print a monthly calendar i have filled in?

Take a screen shot, then print the screen shot from your camera roll.

On the calendar page you want to print:  hold you finger on the home button, then tap the power button and you'll hear the camera shutter sound.  You'll find the screen shot in the camera roll, where you can then print from.

Are you trying to print something you could display on an iPad screen?  If so, display it on the screen, then take a screen shot by briefly pressing the home and on/off buttons simultaneously.  Then print the resulting image from your Camera Roll.

what about the calprint app?