Out of the blue, I can count four ways to go about it. All assume that your world was created with one or more civilisations (meaning races, kingdoms, whatever).
The first option is to focus on a community. It can be a neighbourhood in a large town or in a small town, it can be a village, a religious community (think something equivalent to a village for a group of secluded religious people), or even the royal court.
Imagine how that community works, identify a few characters by function (baker, begger, farmer, warrior, etc) so as to have a feel for the way people's everyday life flows.
Now choose one or two of the locals and give them something they want, whether it is to catch the eye of the handsome baker apprentice or to escape their father's imposition of working in the family farm rather than becoming an apprentice to the carpenter. Let it flow.
Alternatively, let a stranger come to town, whether it's a circus, a salesperson or an old warrior heading home. What trouble can they stumble upon at the Inn?
The second option is to focus on your world's history. When and how were the current limits of the Kingdom settled? Was there a war? Or perhaps there was a joint kingdom that was broken up when the dying king decided both sons should inherit. Did the brothers accept the division? Or perhaps their descendants are now eagerly plotting to conquer the other kingdom to themselves. I mean, to reunite what was wrongly divided. You can either choose to write the story of the division (including those who opposed it) or the story of the current kings. Perhaps you could write the chronicles of the current dinasty! Or the previous.
The third option is to focus on the world's mythology. If the religion is well developed and there are actual gods and mythic heroes (demi-gods or humans who dealt with the gods), you could write the story of the gods (especially if the pantheon behaves like a court of immortal people bickering among each other) or the adventures of the demi-gods and the human heroes.
Or perhaps you want to tell the story of a local 'monster' (say, the three headed creature which is often hunted by the locals) from its own point of view. Or the hunters'.
If you're into short-stories, you could write a collection of legends that explain how the gods' actions created the world as it is today. A bit like the Greek myths that explain the origins of animals, geographical features and constelations.
The fourth option is to focus on the world's geography. If there is a map of the world, surely there are some mountains, volcanoes... inner seas filled with monsters maybe? If you have a Death Valley, write the story of a caravan travelling through it. If there is a chain of mountains, have a nobleman hire a group of mountaineers to safely take his daughter to meet her future husband on the other side. If there is a bay inhabited by sea monsters, tell the story of the fisherman who dreams with capturing more than just fish, earning fame and riches for his heroic deeds.
If I think of a fifth or sixth option, I'll come back ad jot it down. In the mean time, have fun.