I am making a FPS and dont kno how to make him hold a gun showing arms and gun...i also dont kno where to find a 3d model gun...pls help thank you
My opinion:
Download Blender (Free, and works). Or if you have money, or are a student and have a .edu email, you can get any Autodesk program for free. Get one.
Now, model some hands and a gun.
Now make that a child of the FPS Controller.
What you can do, but is very pointless/worthless:
Download someone else's gun and hands/arms.
And do the same as above.
Now, as for shooting, you'll have to learn scripting. So for that. www.google.com, and start learning Javascript or C#.
Good luck!
Start reading here: http://unity3d.com/support/resources/tutorials/fps-tutorial-part1
I think you will find your gun there as well.