if its the same as my 98 GSR then its really easy.

Here is just a quick run down. If your tank isnt pretty much empty...empty it. There is a bolt on the bottom of the tank. Then take out the carpet in the trunk. Under that should be a metal bracket type thing held in by 3 10mm bolts. Remove that and that gains access to the fuel gauge sending unit. Unplug the sending unit wires.

Go under the car, if you have a floor jack put it under the tank so it just touched. Then loosen the 2 straps holding the tank in. SLOWLY lower the tank until you see the filler tubes, fuel pump wires and various other wires and tubes. Now on the drivers side in the rear is a whole cluster of tubes be sure to unplug everything and slowly lower it. If it hangs up a little, jack it up and look around.

Best bet, go and buy a manual. I have that Clymer (sp) that i got for $16 and its awsome, tons of pictures.