Nikon D90 filming mode?

How do i change the nikon D90 film resolution, at the moment its set at 640x480 so how do i change it to its 1080pi resolution?

First, the Nikon D90 does not shoot 1080p. Its highest resolution is 720p.

There should be a Movie Settings option in your shooting menu (the second one from the top in the menu) in which you can control the resolution up to 1280x720, the sound, and focusing.