If you want a chunky guacamole, mash up the avocados with a fork. If you want a smooth guacamole, put the flesh of the two avocados in a food processor and puree.
Mix in the rest of the ingredients and set aside in the fridge for at lease an hour or two before serving.
Make sure that when you cover your guacamole, to leave no space for air between your plastic wrap and your guacamole. This will prevent it from browning.