By being in the sun. Fair skin (as in prone to burning) burns easily, and after a while, your skin develops them. If you burn and you get freckles, that means your skin is more susceptible to skin cancer.
freckles are a person's way of natural sunblock. some peopel just et burned, others get tanned really easily, while others are freckled.
and if your out in the sun a lot alot alot..when you get older youten to get "freckles"..more like little or different sized darker spots sun of too much sun-exposure...
I was born with freckles all over my face! I get more during the summer, when I spend alot of time in the pool and outside. Make sure to wear sunscreen!