Agreed with Moe, reading that link is the best way to start off into the betta world. Beside that link though, the basics (without going into details of why) are:
-Food, Tetra BettaMin is sufficient. A betta generally though desires a varity of food, but does not -need- it to my knowledge. Other food items: Freeze dried shrimp or blood worms, live blood worms, pellets, etc.
-Water conditioner. Our water contains chemicals like chorline and such, a water conditioner takes these chemicals out making it safe for your betta. I have a stress coat that provides the same effects as a water conditioner.
-Water changes. This is something I'm still new at as well, so I wouldn't know of what % you need to change, but you do NEED water changes. Otherwise harmful chemicals build int he water that can harm or kill your betta.
I'm still new as well, so until more experience responses appear I hope I helped a little! Good luck to you and your new betta! *Salute* =)