Making Friends/Social Stuff

Can therapy teach me how to make friends? I am very alone in my life and I am tired of watching everyone else at work go out and have fun together and not invite me. I want to go with them but it is like I don't know how to make it happen and I think they think I do not like them even though this is not true. I have come to the conclusion that friends on internet forums aren't much of a substitute for real people in the same room.