Projectile Script

Hey guys, OK so, I have made a very simple platform.
A large area with a 1st person controller walking around on top now the next thing would to add a weapon.

I have no knowledge of Scripting, all but a small amount on HTML I did a year or two back. I have made the empty space and added it to the camera, now all I must do is write up the script and attach it to the thing. This is where I am lost! I have no idea on how to write a script!

Can anyone help me out on this?

After that I would then need to add enemy who will shot back and move ect.

Thanks

Can anyone help?