I need to evict my roommate for non-payment of rent for last 2 months. I am the only one on the lease. He moved in after I had apartment for 4 years. How do I go about this?

Go to yoiur local courthouse or housing court and ask for the exact procedure. It varies from place to place. Generally you have to give him a pay or vacate notice of 3-10 days. If he hasn't vacated, then you go to court for an eviction order. The court issues the order (he still has a chance to pay up) at which point you hire a sheriff to enforce the order and remove him.