Because you're new...
Priming sugar is what give your bottled beer the fizz (carbonation). You add it when you're bottling your beer. Yes, you can use table sugar etc. I use dextrose as it dissolves easy and it's fairly cheep at the grocery store 2 minutes from my house.
Next time...
If you search for any question with google and add "homebrewtalk" at the end of it you'll get a lot of good information. I went through a good several months of questions without having to start a new thread.
Happy brewing!