Press
start in the main hub and go to your loadout. Your perk board is the place where you can adjust your class to your liking. At first, most of the board is still locked. Keep leveling your class by playing so that you unlock space to add more modifiers. You see which level you’ll have to reach in the “locked space” to unlock the space.
In the 8x4 grid, place the modifiers however you like, linking certain upgrades to one of your three skills (you’ll see a little link/line to that skill). Some modifiers only link to certain core abilities (like rifle mastery only sticks on the basic rifle core mod). Mix and match until the whole board is full, et voilà!