https://www.foodnetwork.com/recipes/jamie-oliver/salted-preserved-lemons-recipe-1955868
I just slice the lemon into 4 wedges (I don’t bother trying to keep it together) which I find packs into a jar more easily. Then I add enough salt to completely cover/surround the lemons, especially on top. This recipe is great with meyer lemons.
It pretty much stays there, you don’t need to do anything. I always keep it in a cupboard, out of direct sun. Other than that I don’t do anything. After a few years the flavor profile gets muted and it’s time to make a new batch.