Instructions
Finding the Ring
Work through the main quest line of "Bloodmoon" until you reach the final quest, entitled "Hircine's Hunt." You begin the main quest line as soon as you enter Solstheim, which contains 11 to 12 quests depending on which paths you choose. All, however, lead to the "Hiricine's Hunt" quest.
Go to the Skaal Village and talk to the shaman Kirst Wind-Eye, who will tell you about the Bloodmoon Prophecy.
Go to sleep in a bed somewhere immediately after talking to Korst. You will be awakened by werewolves surrounding your bed and then teleported to the Mortag Glacier. You will face Hiricine, who will tell you that you and three other people must make your way through the glacial maze, but only one will survive.
Work your way through the glacial maze, which is fairly straightforward, using the help of the three other characters. You will need to fight several powerful werewolves before you can proceed. You will eventually make your way to the Inner Circle, where you will meet Tharsten Heart-Fang.
Defeat Tharsten Heart-Fang when he attacks you to be given the Hiricine Ring, which can turn you into a werewolf. Continue along the quest until it is finished. You will be required to defeat Karstaag the frost giant and the hunter Hiricine before you are let back out into the main game world.
Using the Ring
Equip the ring to turn yourself into a werewolf for six hours. Equip it where no non-playable character can see you, like in an alley or an empty house. They will attack you if they see you.
Take off the ring to become human again or wait six in-game hours -- six minutes in real time. Do not take the ring off around people.
Press the jump button to jump twice as high as a human being when wearing the ring. Press the main attack button to slice at enemies.