This tutorial uses the distro provided by adafruit, if you dont have the distro up an running re-visit one of my old tutorial on raspberry pi.
Step 1: Parts
SDA >>> SDA
the diagram below is from http://elinux.org/RPi_Low-level_peripherals
Step 2: Tools
sudo i2cdetect -y 0
this will scan all devices connected to the I2C bus. it should look like the pic below. if you see that i2ctools are not installed
run the following comand
sudo apt-get install i2c-tools
sudo apt-get install python-smbus
sudo apt-get install python-pip
sudo pip install rpi.gpio
wget -O geekman-python-eeml.tar.gz https://github.com/geekman/python-eeml/tarball/master
tar zxvf geekman-python-eeml.tar.gz
sudo python setup.py install
note down the address of the I2C device that you have connected. in this case i have connected a temp. sensor PMODTEMP2 from digilent.we use the sumbus function for I2C communcation.