The following will allow you to use the VP1 Vintage Phaser to its full potential:

1.  Connect your guitar to the input of the VP1 with a 1/4" instrument cable.
2.  Connect your amp to the output of the VP1 with a 1/4" instrument cable.
3.  Adjust the RATE control to determine the speed of the phase shifting effect.
4.  Adjust the TONE switch to the bottom position for a negative feedback (delayed signal is inverted before being fed back to the original signal), or to the upper position for a positive feedback (delayed signal is not inverted).  A positive feedback will give you a more detuned character.

Experiment with different rates and feedback settings until you achieve the effect that sounds best to you.