Bettas are insectivores. Their natural diet is insects..
Do you mean people food? I wouldn't do that, fish food has better complete nutrition for a fish.
What brand are you feeding him?
Many betta don't eat at first in a strange new place, it's normal for them to go a week without food.
You should look into a pellet food, such as Hikari, Omega One, or New Life Spectrum, designed for betta specifically. Once a week, you can feed frozen brine shrimp or bloodworms. Avoid freeze dried foods.