Most social skills are learned, so it's good you want to expand your knowledge. I'm not going to tell you that it's easy, because for some people it's not.
I read the newspaper every day; I go online and come here; I open myself up to memorizing trivia facts - all these help me open a conversation with someone.
When you want to practice, go up to someone you kind of know and say - hey, how's it going? Then you say something like - did you know the Killer Whale is actually a type of dolphin? Weird, isn't it?
Look people in the eye - smile - ask them questions - listen to what they have to say. Nothing is more attractive than a great listener.
Practice saying hi to people you don't know. The more you practice, the easier it will get. Good luck. And remember, everyone has felt the way you do at one time or another.