A humidor is a box that tries to keep the weather still. The usual lining is Spanish cedar, which takes up and gives back moisture after you season it. A hygrometer tells you the relative humidity; a humidifier, packs, or beads try to hold it.
There is no single correct number. Makers, shops, and collectors commonly talk about a band from the mid-60s to low-70s percent RH. Older American habit said “70/70.” Some Cuban storage guidance sits a little drier and cooler. Pick a stable point in that neighborhood and stop chasing it. Details live on the humidor article.
Smoke Rings lists humidors in the shop. The wiki does not sell cigars to put in them.