You need to access the Event Fx for video - it's a tiny . . .
Entire Clip - Event Fx for clip, located at the extreme end of the Event - icon looks like a . . . square with arms outstreched, honest!
Entire Track - Event Fx for Track, located in the track header, looks as the same above
Click on this and choose one of the colour item/s plugins. "Black and White" is a neat place to start.
But you made be after wanting more "contrasty-type" colours. Start adding and trying different plugins from the Plugin Chooser - you're gonna have a lot of fun!
My best advise is the V4 manual. It's free and can be downloaded from SoFo site. It's chock full of fab stuff . . I highly recommend it.