hmmmm nice encoder!
Ok so the encoder sends out pulses, right? And your microcontroller can detect these pulses already, right? Well after each pulse, your robot has traveled Z distance.
So if your robot travels in the X direction, add Z to the X counter. If your robot travels in the Y direction, add Z to the Y counter. As long as your robot only does 90 degree turns, this will always work. If you are confident in math, you can do trig to go at any angle. If you dont know what you are doing, just stick with 90 degree turns for right now, and dont use the quadrature feature.
Now someone else recently asked about calculating distance and velocity of your robot with an encoder:http://www.societyofrobots.com/robotforum/index.php?topic=1051.0
You will find it useful.
Ok so you now have X and Y data from your encoder, right? For example:
Basically the counter always knows the location of your robot. Put that data into excel, and hit the line graph button. This will give you an instant easy to view map.