The Companions of Jorrvaskr might be the epitome of what it means to be a Nord in Skyrim. The group of warriors traces their history back to Skyrim's founding days call upon a rich heritage of courage and martial skill.
They're a tight-knight group that offers a chance to earn gold in combat, solving problems from coin around the province. For all of their honor and glory, however, they've got a few dark secrets that you might uncover. If you want to join them, head over to their home city of Whiterun and let this guide point the rest of the way.
How To Start Take Up Arms
You will have to complete the quest Take Up Arms to join The Companions. Go to their mead hall, Jorrvaskr, near Dragonsreach in Whiterun to start the quest. It's a long building that has an upturned boat for a roof.
You'll need to go inside and look for their leader, Kodlak Whitemane in the Jorrvaskr Living Quarters on the south side of the building. He's having a quiet conversation with Vilkas, a distinguished Companion. Introducing yourself will begin Take Up Arms.
You might've come across a small group fighting a giant near Whiterun when you were warning the Jarl about Helgen in the quest Before The Storm.
If you'd stopped to help out or just wanted to see who the warriors were, one of the group's senior members, Aela the Huntress, will approach you and give you the chance to express interest in the group. You will receive the miscellaneous objective "Speak to the leader of Jorrvaskr" that will point the way.
How To Complete Take Up Arms
This quest isn't very exciting, though it does introduce you to The Companions' most prominent members starting with Vilkas, a young and intelligent Companion. At Kodlak's request, he brings you to the sparring yard for some training and to see what you're capable of. That involves showing him how hard you can swing. Beat him into acknowledging that you have the right to join The Companions to progress. Don't be concerned about having a tough fight; he won't fight back.
This part of the quest can be buggy. Try to keep any companions away from the sparring as they might think there's a real fight on and intervene violently, interrupting the quest.
Magic damage will also interrupt the quest, including damage from enchanted weapons. Mundane weapons will get around this.
Vilkas will send you to Eorlund Gray-Mane, a talented blacksmith working the Skyforge, an important part of Jorrvaskr. After learning more about him, he'll ask you to deliver a shield to Aela the Huntress, down in the Jorrvaskr Living Quarters. You'll find her alongside another senior Companion and Circle member, Skjor. After introductions, they call over Vilkas' muscle-headed twin brother, Farkas. He'll bring you to the barracks where you can sleep for free. With that done, you've joined Companions. In a purely probationary capacity, but it's a step.
From here, you've unlocked the ability to ask the Companions' leaders for work, a way to earn gold from completing randomly-generated quests. You'll need to complete at least one to reach the next stage of The Companion's story.
Each Companion leader will offer a different set of quests. Ask around to see which jobs you would enjoy the most. The pay won't change, though.