I find it a lot easier to communicate online than in person because it gives me time to think about what I am going to say, also there's no eye contact which helps.
Try having a conversation about something you know you're interested in, for example if there's a show or movie you really like then that should lead to a conversation. I feel that when I am discussing something I'm interested in I can go on and on.

I find it difficult to communicate with people in person, I've spent a lot of time alone or with people I know so when it comes to having a conversation outside my comfort zone and being social at times I am a little shy or lack eye contact, but I notice the more I do it the better it gets. Try talking in online forums such as these, it's not necessarily direct contact but it helps communicate. Then work your way to one on one contact with someone in particular, and so on.

Don't pressure yourself, it's okay to keep it short if necessary. Practice it often and I am sure within time you'll find that it will become easier.