How do you join the great khans on fallout new Vegas?

To join the Great Khans in Fallout: New Vegas, you first need to progress through the main questline until you reach the "Back in the Saddle" quest. After that, head to their camp located in the northeast of the map, near the Red Rock Canyon. You'll need to complete a series of tasks for them, including proving your worth and gaining their trust by participating in their activities. Completing quests like "Bitter Springs" will also solidify your standing with the Great Khans.