Slide the nut, back ferrule and front ferrule, in that order, onto the tubing as shown in the image. The wider end of both ferrules faces towards the nut.
Insert assembly into the receiving port. Push the tubing into the port until it bottoms out.
Slide nut and ferrules down until the threads engage. Tighten using the nut to finger-tight.
Place a wrench on the nut and tighten the fitting to: 20 in*lbs (2.26 N*m).