How to use pylab to plot figure()?

#quote from MIT 'introduction to computation and programming using python, Revised'
import pylab
principle = 10000 #initial investment
interestRate = 0.05
years = 20
values = []
for i in range(years + 1):
values.append(principle)
principle += principle*interestRate
pylab.plot(values)
pylab.title('5% Gowth, Compounded Annually')
pylab.xlabel('Years of Compounding')
pylab.ylabel('Value of Principle($)')
pylab.show()