Need suggestions for camera for magazine publishing

I'm a newbie who would love to have some magazine articles published.
I was speaking with a publisher at a recent Writer's Workshop and he
asked me to, along with my article, submit photos of a minimum 300 dpi
at the published size (bigger the file, the better).

I do have several cameras but they are all older and of minimal
quality. My digital camera is just over 3 megapixels and I'm guessing
that it is entirely inadequate.

I'd love to get a new, higher resolution digital camera for this
purpose but have no clue as to what I should get or even if a digital
camera is the way to go.

I'd appreciate your thoughts and suggestions.

Thanks for your help.

Sandy