Welcome to the DIS!!! You will find a wealth of information here simply for the asking.
We enjoy the Electrical Water Pageant. It is very cute. The first time we saw it, I told my DH it was "like the frosting on the cake" and it is Free!!!
The best place to see it is from the beach of one of the resorts it passes by. It is occasionally canceled in inclement weather, but for the most part it runs every night.
This past October be actually saw it from 'OHana as we were finishing dinner. It was nice to see, but not the same as being on the beach since they do not pipe in the music.
Have Fun!