https://nucleuspowered.org/docs/configuration/permissions.html
Nucleus makes it really easy to get a basic setup going. Thats a pretty good guide.
If you use the plugin chatUI.
Chat UI - A UI toolkit for the vanilla chat box
Watch that demo video as well to see how to add and delete perms. `
And the plugin griefprevention is probably what you are talking about with shovel based claiming.