Best exposure for taking photos of planets?

I want to take pictures of the planets Venus, Mars, and Saturn alignment. I have a decent point and shoot digital camera. There is a setting where you can manually set the shutter speed and aperture. I'm not really sure what setting it should be on. The instructions say the shutter speed can go from 30 to 1/2,000 seconds and the aperture from F3.5 to or F8.0 with the zoom set to the w side. And F4.4 or F10 with the zoom set to the T side. If you have experience with this, help would be appreciated. Thanks.