If you have never had a bike hub apart, or have never adjusted bearings, you might be better off taking the wheel to a bike shop. If the shop is friendly, or if you can make an appointment with them to watch them do the swap, then they could show you how. It's a 5 minute job, maybe 10 minutes if they explain it.

Otherwise, a book store should have a good bike repair manual to explain things. OR, just go here:
Rebuilding Bike Rear Hubs
As far as building the GEBE kit, just follow the instructions very closely. The only tricky part is installing the drive ring on the wheel. I used diluted "concentrated" liquid dish soap (about 1/3 soap and 2/3 water, so it can flow well) and a q-tip to lube the drive ring slots and spoke right before using the 4 in 1 tool that they supply to pull the spoke into the slot. I used a piece of heavy felt (meant to go on the feet of furniture to protect the floor) to protect the drive ring from the screwdriver. You can use some heavy cardboard or something similar.
Some builders say they have problems centering the drive ring on the wheel. I followed the instructions and alternated the spokes I worked on just like GEBE tells you to, and my ring was almost perfectly centered. To check centering, hold the wheel by the axles and spin it. See if the drive ring looks nice and smooth as it goes around, or if it wobbles up an down. It can move up and down some, so if it looks close, then you are good to go. If you see a fairly bad wobble or worse, let the wheel slow down and try to find the high spot. I take a soft rubber mallet and lightly tap the high spot 2 times and check it again (use the weight of the hammer only or you can mess up your spokes). This can take a little while and it may get worse if you tap the wrong spot. Just be patient, go slow and take a break if you need to. You could also measure to find the high spot, but that's not as much fun!
If you have any questions, come back and we will help.
The GEBE kits are great, I have the Tanaka 32cc, just installed it yesterday and I have only taken it for a quick test run so far, but it all works perfectly with no vibration and it's fast.
Have fun!