Resets! Where would we be without them? Naked and level 1, that's where. So, now that we've established that we -have- to learn these things, on to the good stuff. You can addresets in any mode, but redit is the easiest because you can 'x' to see the list but if you are in another mode, type
'showresets' to make sure it is correct.
Doors addreset door [dir] [closed|locked]

Make sure you set the door as type door, otherwise it won't work!

  addreset  rand [num-dirs]

This randomizes the exits. Ex: Stock Moribund uses random doors.

  message [min_lev] [max_lev] [text]

I've still never messed around with this much, I believe its broken or I'm just using the wrong syntax but it tends to bug area files.

Objects addreset obj [ovnum] [max number in room]

This adds the desired object to the room.

Mobiles addreset mob [vnum] [max number in world]

This will add the mobile to the world, one per repop till the max number exists. I mention 'world' because if they aren't stay_area, they still count towards this max.

Mobs and Objects addreset equip [mvnum] [ovnum] [wear location]

This gives equipment to mobs for them to wear. They gain any benefits from the eq. When you 'x' it will probably show the wrong wear slots, don't worry about it.

  addreset give[mvnum][ovnum]

This is how you give eq to shopkeepers to sell. If the mob is killed the eq disappears.