I would suggest that you buy you hamster pellet food. So that anything else you give him/her will be a treat.
I would only give your hamster treats every few days - for instance - every three days give him/her a few seeds or another kind of treat.
Important tips you should know
Hamster loves to exercise. They are naturally energetic and will do a lot of running. So make sure you provide all necessary equipment such as hamster wheels or adequate size of running space for them to
Hamsters are nocturnal creatures (active at night) so they need peace during the day to sleep. It is highly recommended to place the cage away from draughts and direct sunlight.
The cage floor should be covered with adequate layer of bedding. You can use the commercial wood shaving as they are absorbent and nontoxic.
Hamster also needs privacy during their resting time. Build them a simple small room for them to sleep. A small box will be a good idea.
Feed your hamsters adequately. Make sure they have enough food and more important water supply.
Wash the hamster cage once in a week. Keep the cage clean to prevent any infection risk.
Bathing your hamster are not recommended. Don't worry, they can clean themselves.
Build a good relationship with your hamsters. Talk to them, hold them and playing with the will keep the hamsters happy.