The outpost is located to the west on your in-game map. Head that way and kill the few enemies that show up, making sure you grab the Raritanium in the little alcove. In the next area, there will be plenty of enemies to battle, some of which are dropped in by a dropship. Make sure you be careful of the turret, who won't fire until you get close enough.
Once the turret is clear, man and use it to destroy the two grates, one of which has some Raritanium and the other blocking a Grav Target. Connect that target with the one in the air, then while you're sitting in mid-air, connect the other two and ride the beam to the cliff. There are two enemies sitting on the ledge across the gap, so take them out and then use the Tether to get over there.
Keep moving forward, killing enemies and using the Tether to cross gaps until you get to a big open area. You'll have to do battle with a bunch of enemies here, including more being dropped in by a dropship. Once they're all dead, go to the opposite end of where you landed and turn the bolt crank to lower the Grav Target.
With it lowered, shoot it with the Grav Tether and then connect it to the highlighted one. While you're in the beam, shoot the one to the left of the second one you shot, then connect it to across the canyon. There will be more enemies here, including another turret, so be careful here. When it's all clear, man the turret and break open the grate to find an Infobot that will tell you about the arena. You're now back in the central area.
