To train your betta, it is better to use pellets.
1) I pinch the pellet about one centimeter above the waterline in his tank.
I hold my pinched fingers for ten seconds before i drop the food.
I let him relize that my pinched fingers mean food.
2) Then, try pinching the pellet in such a way that he can see it in between your fingers, and hold it there for about twenty seconds (with him watching) then drop it into the tank.
3) Then, i wait holding the pellet, and hopefully he will get tired of waiting, and he will try to jump for it. (be careful, if he accidentally "bites" your finger, it may startle you)
That is my advise. I would reccomend step one for a week, step two for a week, and finally step three forever