Me and my friend want to make the same game with unity

How can me and my friend work on and make the same game with unity when we both have are own pcs is there a way for us to be connected like if I want to make the map and he want to do the NPCs is there a way me and him can both work on it?

If you are using Unity 4.0, you should be able to use SVN to share your project. With 4.0, Unity enabled metafile support (Project Settings/Editor/Version Control) for the free version. Previously it was only available on Pro. You will need an SVN server. We purchase space on a server for about $4 US a month. There are sites that will host your project for free if you make it public. Here is a reference page on SVN:

Using External Version Control Systems with Unity

Note you will still have problems sharing binary resources like scene files. One method that might work for the two of you is to setup an ownership file for the scene. Also make prefabs out of anything and everything. That way changes can be made to the prefabs without changing the scene(s) files(s).

There is a liecence you can buy for I think 500$ that allows you to share the free version of unity. or you can mail files back and forth and update manually.