So, basically you want to make another MSN messenger. I suggest to dump this idea.. Whats the point? If they want software like this they use MSN, or Yahoo messenger, or ICQ or Gtalk.. list goes on long. And these are far too strong companies to compete against. They also have web based clients if you wanted to do that.
You also need a high-end server(s) and a dev team, you cant do program like this alone, especially if you don't know anything about coding.. both of these cost a lot of money, unless you make it open source. But to make it open source you still need to make a good starts, so other coders thing "Hey, this guy knows what he's doing. Lets help him"..


Anyway, if you do want to.. try it you should look into some coding language. Some say VB.net is easiest to learn at first. I very much think otherwise. I found C# and C the easiest, even C++ was easier than vb.net, but probably just because I learnt other C languages first. There are a lot another languages, but these 4 are the most used ones. Most powerful and understandable syntax..