My power supply unit exploded D: how can i change it for another?

umm....im 14.... but my mum wants to help me with my computer...ill tell you the story

(if ya dont wanna know....youll find the question at the bottom)



i was round a friend, emma's house on her birthday....someone gave her a compter thingy

(i cant remember the name(my mum calls it a tower)) so she gave her old computer to my other friend , jenny, so she could find someone who wants it



so after all that i ended up eith it....and it was working fine but im a idiot so i switched the red button at the back....basicly....KABOOOM *computer clicks off*



so...now im on my old computer wich has like 2500000 viruses and when you click on internet explorer, it loads 200 of them



my mums plan is to change the power supply unit in the exploded compute....for the one in mine....so the exploded computer works again



one problem

how do i do this?

oh...and please dont say its not a god idea just because im a teenager....im pretty smart....but tell me if it might, like, end the world or something less dramaticMy power supply unit exploded D: how can i change it for another?
As long as the power supply will physically fit into the computer case (the tower) and has the right amount of pins for the main power everything will be fine.



To determine this you simply open the computer up and find the main power input:

http://www.hardwarezone.com/img/data/art



Count the pins (holes) and make sure it matches the power supply's main power cord (again count the holes):

http://z.about.com/d/pcsupport/1/0/1/7/-



If the motherboard is 20-pin, you need a power supply with either a 20-pin or 20+4 pin main power connector.



If the motherboard is 24-pin, you need a power supply with either a 24-pin or 20+4 pin main power connector.



That is all you need to make sure of.



If you installed a PCI or PCI express video card at any point (it will look like any of these http://images.google.com/images?hl=en%26amp;so )

Then you'll need to make sure the power supply has enough power to power the card as well as the rest of the system. If have not done an upgrade to the video card, then you don't need to worry about that.



To install a power supply you just have to unscrew the power supply from the mounting bracket inside of the computer case, remove all of the cords that go into the power supply from the motherboard, take the old power supply out, place the new power supply where the old one was, screw the screws in to mount it, and plug everything back into the motherboard.