This script will ask for an input of a year. It will then take that input and return the calendar for that entire year.

import calendar

print "Show a given years monthly calendar"

print ''

year = int(raw_input("Enter the year"))

print ''

calendar.prcal(year)

print ''

Try another year by adding a while loop into the script.

import calendar

while True:
print "Show a given years monthly calendar"

print ''

year = int(raw_input("Enter the year"))

print ''

calendar.prcal(year)

print ''

raw_input("Press enter to go on ...")

For more things to do with the calendar module, please see the official documentation.