I need to know where the ribbons inside my tower

the only way to tell is to open the case, it's usually not very hard. mostly 2-3 screws or nobs on the back or some have a handle on the case you slide back and the side will come right off.

IF YOU DECIDE TO DO THIS: make sure you are properly grounded. you can buy a strap that has velcro one the end that goes around your wrist and an alligator clip on the other that you clip on the case, or (and i know this sounds wrong but it works), make sure your computer is turned off, but leave the cable plugged in. the round plug on the cable is a ground connection. once you take the cover off put your hand on the power supply or the frame before you touch anything inside the case. 1 static shock (like when you walk on carpet and shock someone) is enough to blow a motherboard, hard drive, ram chip, video card or basically any part in the pc.

you'll need at least 1 screwdriver , probably a small phillips head, to get the case off, a small bright flashlight, a small magnifiying glass wouldn't be a bad idea, and a friend to help wouldn't be a bad idea also. but basically all you can do is gently grasp the cables with your hand and trace where they go. one end will go to the device and one will go to the motherboard or power supply.

when i was teaching pc upgrade and repair i always told my students to get a piece of paper and draw a picture of where things were. on most motherboards if you look closely, (this is where the magnifiying glass comes in handy) plugs, ports, and slots are usually marked to tell you what plugs into that spot. just go slowly and take your time, don't pull on any thing very hard, the cables should move pretty easily, but a small tug in the wrong direction and you could unplug something. this is where the map come in handy.

also if you take any cards or chips out DO NOT touch the brass ends. this will leave grease on the ends and will start corrosion in the slots or on the chip or circuit.

There are no ribbons running inside your pc. The flat cables are there to connect the hard disks, floppy and the optical units to the motherboard.
The hard disk must be connected to the first socket on the motherboard (labeled ATA1). The blue connector of the cable goes to the motherboard the other head plugs into the device.

Here is a link to an inside view of your computer, maybe this will help:-
http://support.gateway.com/s/CASES/WME1T493-001/WME1T493-001iv.shtml
Also a link to your user manual:-http://support.gateway.com/s/PC/R/1009151/1009151ul.shtml