You need a 1 gallon or more (no less) tank, and hgh quality food. If your room gets below 75F you'll need a heater.
Males MUST be alone, ALWAYS. Females can be in groups, assuming you have at LEAST 10 gallons, and you can not have more then 6 or LESS then 4 in a 10 gallon.
Without filtration, you'll need to do 90% water changes once a week
Read the care articles posted at the top of the forum ^___^
Katy
**EDIT** Personally I prefer Hikari brand betta food, though I hear the chiclid chow from Hikari is good for bettas too. I also feed frozen bloodworms every other day.
Personally, I would not keep a betta in less then 2.5 gallons, with lots of real plants... The bigger the better.