Unless your dog is a super exuberant retriever, Fetch is generally a learned activity.

First, introduce the ball. Make it exciting and engage your dog. Roll the ball a few feet and chase it yourself. Don't forget to make fun noises (growly noises can incite play). Eventually, your dog will join the fun and she will start to mouth the ball. Reward your dog by petting her and running around in a play-like manner. Soon, you can toss the ball a couple feet and she'll run to it herself. Does your dog know "Come"? What about "Give" or "Drop it"? The hardest part is getting your dog interested in the ball. Once you've got that done, the rest is just a matter of simple training. Dog gets ball. You say "Come". Dog comes. You say "Give". Dog releases ball. Heck, you're already playing fetch!

ETA: Just noticed your pup is a Beagle. From my experience, beagles are pretty split when it comes to balls. Either they love 'em or hate 'em. Try using a stuffed toy or rope instead.