The best way to pick random integers between 1 and 15 is this way:
import random
# selects one random integer from 1 to 15
pick = random.randint(1, 15)
Then you set up one 'endless while loop' asking the user to enter the guess. Use series of if/elif statements comparing the guess with the pick. If the guess is higher or lower let the user know and stay in the loop. If the guess is correct break out of the loop and then tell the user that the guess is correct.