took apart dell computer and I don't know how to set it back up?

First, does the screen show anything? Second, what lights light up? There should be a light on the motherboard (main circuit board). It should have at least 2 (maybe more) of the power supply cables plugged into it. The hard drive and cd drive will also need plugged in.

A clearer picture of where the cables are plugged into the mother board would help too. Good luck!

well I can say this for any one who has put a computer together (me) multiple times is that the first time is the hardest. You need to pick up that fat old motherboard and psu manual and figure out which pins go into which. Just make sureto place the pins in their correct spot to get enough power into the computer for it to boot.

if you do not have the manual for the computer then just go to dell's website and enter in the service tag number or search for your model of computer and download the pdf of the manual !

it will show you exactly where to insert each connector .

yes provide more pictures and also did you connect p1 and p4 already? Connect the P1 into the connector on the motherboard that has 20-pins or holes sometimes motherboards label this in small print as ATX POWER there is a notch on the connector which means it goes in one way. P4 connector is a square 4-pin connector also with a notch to connect one way only its usually next to where the cpu fan is motherboards will label it in small print ATX12V. Also for the hard drive there is 4-pin connector called a molex connector that is keyed and will go in one way make sure it is oriented properly.