New DM and I wanna try running a more lighthearted campaign for a few friends and idrk what to do. Any tips?

So I've played in like around the first quarter maybe? Of one campaign and im lookin to run a less rule heavy and more just fun campaign for a few online friends and i really just cannot think of what sort of plot or ideas I should be doing.

I myself have never dm'd before so if anyone here has any tips or something for making a story like this id really appreciate it just so I can get a grasp of what I should be doing.