I know you posted this awhile ago, but I have some information for you assuming the betta is still alive and well.
Some basic things you should know.
Bettas come from Thailand, and are a tropical fish. This means in order for them to be healthy and active they need heater water. At least 76F- with 80F being preferred.
Bettas need filtered water. I would recommend you go down to petcetera and pick up either a 10g tank kit- They cost only 39.96 and come with tank, hood, filter, and food.
Bettas need Water Changes once every 2 days in a small unfiltered tank. This means putting the betta into a cup gently, emptying and rinsing the bowl, and refilling with water the exact temperature it was before, within 1 degree or it can shock the fish to death, and adding a good quality water conditioner to the water so it doesnt die from chlorine poisoning.
A really good site to go and get information is Fish Profiles.
Bettas are easy to keep ONLY if given what they need.
You shouldnt feed hamburger as this will spoil the water very quickly and cause ammonia levels to rise and your fish will die of ammonia toxicity.
You should purchase a good quality flake food, and supplement your bettas diet with some bloodworms, either frozen or freeze dried.
I hope this helps you some. Good luck to you!