The two lines you might want to edit are the following:

# i2c bus (0 -- original Pi, 1 -- Rev 2 Pi)
I2CBUS = 1

# LCD Address
ADDRESS = 0x3f

after installing i2c-tools you can use

i2cdetect

 to find your bus number, and then 

i2cdetect -y 1

or whatever your bus number is, to find the address of your screen.

you can install the python smbus library with pip as well:

pip install smbus