Make sure you watch over your hamster when he is out of his cage. They are not climbers and have been known to fall off tabletops and shoulders. They are not used to heights and do not have a sturdy tail, which keeps them balanced. It is also said they are nearsighted. One fall can be deadly to a hamster.
Hamsters are like squirrels in that they store their food.
They have pouches inside their cheeks, which stretch. These pouches can hold half a hamster's weight in food. In their cage, although they don't need to store, they will fill their pouches and then empty them, eat some of it, and then probably hide the rest. This means you will probably have to clean the hiding places daily to prevent rotting food. Your local pet store will carry hamster food, which is a good basic combination of seeds and cereals with some dried vegetables added.