Janaki provided you with a list of old posts...the info on P&B Colon Cleanse is the second one she listed. Make sure to also read the first one if you experienced any problem with the cleanse when you attempted it before.
As for timing the shakes with meals...it's best to take the shakes on an empty stomach and then refrain from eating for about an hour. Also make sure that any herbs, supplements of medications are not taken within an hour either side of the shakes. As you move up in the number of shakes you take a day, it's best to figure out a schedule of when you're taking what and stick to it pretty closely.