<<<where I must put the .js file (in extensions ? )

Yes, into the extensions.
than open the camera1.nod adjust the camera x/y/z and the target x/y/z
Hit run and the camera circles around the target (if speed>0 and its not on Stop)


EDIT: IMPORTANT: You have to use the last V4 the earlier Nov version has a bug in "setCameraAnd Target"