Make a selection with WorldEdit, using a wooden axe that you receive with //wand. Right clicking will set one corner, left will set the other.
Use /region define {whatever you want the region name to be}
Then /region flag {whatever you want the region name to be} {and choose from the flags below} {allow/deny}
Available flags: passthrough, build, construct, pvp, chest-access, pistons, tnt, lighter, use, vehicle-place, vehicle-destroy, sleep, mob-damage, mob-spawning, deny-spawn, invincible, exp-drops, creeper-explosion, other-explosion, enderdragon-block-damage, ghast-fireball, enderman-grief, greeting, farewell, notify-enter, notify-leave, exit, entry, lightning, entity-painting-destroy, enderpearl, entity-item-frame-destroy, item-drop, heal-amount, heal-delay, heal-min-health, heal-max-health, feed-delay, feed-amount, feed-min-hunger, feed-max-hunger, snow-fall, snow-melt, ice-form, ice-melt, soil-dry, game-mode, mushroom-growth, leaf-decay, grass-growth, mycelium-spread, vine-growth, send-chat, receive-chat, fire-spread, lava-fire, lava-flow, water-flow, teleport, spawn, potion-splash, blocked-cmds, allowed-cmds, price, buyable, allow-shop
P.S. Do not include the {Braces}
P.S.S. Do not give OP/admin to anyone willing to help you, they will destroy your server.