3d or 2d?
3d: create a sprite that fills the camera (go here: http://blitzbasic.com/codearcs/codearcs.php?code=456 colour it black and fade its alpha.
2d: bit harder. You'll need this: http://blitzbasic.com/codearcs/codearcs.php?code=659 or this: http://blitzbasic.com/codearcs/codearcs.php?code=658. In fact, the graphics code arc is full of stuff you could use.
if you're successul, post em here so we can see.
3d: create a sprite that fills the camera (go here: http://blitzbasic.com/codearcs/codearcs.php?code=456 colour it black and fade its alpha.
2d: bit harder. You'll need this: http://blitzbasic.com/codearcs/codearcs.php?code=659 or this: http://blitzbasic.com/codearcs/codearcs.php?code=658. In fact, the graphics code arc is full of stuff you could use.
if you're successul, post em here so we can see.