search the forums, there is a ton of info on adding candi sugar to your brew...
dark candi will definitely make your brew dark... adding beet sugar (basic table sugar) will work, but i wouldn't go any higher than 10 - 15% of your fermentables with straight table sugar (boiled in water to sanitize first, of course).
If you'd like to lighten your beer even more, make your own invert sugar. It's totally easy, and makes the sugar easier to eat for the yeast. If it's invert, you can go up to 20% of your fermentables without creating any unwanted flavors.
i'd save that dark candi for a future brew! it keeps for a long time, and if you like Belgian brews, you'll end up brewing a dubbel or strong dark eventually...