To become a werewolf in Skyrim you must first join The Companions, that have their headquarters in the city of Whiterun. You will first meet the clan just outside Whiterun, where you can see them fighting with one of the giants. If you aid in the killing of the giant or approach the group afterwards, you are approached by Aela who gives you more information on what and how to join The Companions.
Joining The Companions is an easy task and is achieved by talking to Kodlak in The Companion headquarters Jorrvaskr which is just up the steps on the right from the market in Whiterun. After accepting and completing all the quests from the leaders of The Companions, you will be given a final quest to collect a few items before meeting the inner circle of werewolves in the Underforge.
The Underforge is located at the back of The Companions headquarters, you will see a door cut into the rock which is under the forge. You must enter the Underforge at night where you will finally meet the inner circle of werewolves, and perform the ritual of drinking from the fountain of blood.
Drinking the blood will enter you into a mini sequence of you playing as the werewolf you have now become inside Whiterun. Being a werewolf is always a brief event and can give you some great strength, when in those tricky combat situations against multiple opponents. You can turn into a werewolf at any time, but must be careful when and where you allow this transformation to take place.
Benefits And Disadvantages Of Being A Werewolf In Skyrim
The benefits of being a werewolf in Skyrim are your health and stamina will be increased by 100 points when you transform into the beast, you will also become faster at sprinting and your hand to hand against enemies is greatly increased.
You will also have a couple of additional shouts which generate fear in your opponents that makes them run away, and a shout which allows you to call other wild wolves to come to your aid in battle.
The disadvantages of being a werewolf in Skyrim is that you cannot equip armor or loot items of dead victims. You will not be able to engage in any conversation with NPC's, and they can either become very scared or hostile towards you.
Being caught transforming into a werewolf is a major crime with the guards, and any enemy that is equipped with silver weapons does greater damage against you. You will also only be able to regain energy by eating your victims, which can be a slow process especially in the middle of combat.
Being Cured From Being A Werewolf In Skyrim
To be cured from being a werewolf which is called Lycantrophy, you must speak to Aela The Huntress in The Companions. She will offer you one final quest to cure the disease and once completed you will never be able to become a werewolf in Skyrim ever again.