How to start making a world

So for a long time I've been wondering and trying to start writing a building a world. I've been playing DND for a bit of time and interested in writing fantasy as well. I'm interested in using the same world for my campaigns and writing. I have some general ideas, which I'll be listing below. But nothing really concrete to use as a basis and start creating a world to base off of. So for my world, the DND version has the different races through several kingdoms on a large archipelago of islands centered around one central island created by the overgod. The version with my book is very much similar but there are only humans and maybe some more races but nothing too fancy. I don't really have any idea if this is a good enough start or even make any sense. Please help.