How do I properly connect the water supply line to the 90-degree elbow fitting?

For copper tubing only: Slide the nut and ferrule about 1 inch (2.5 cm) onto the copper tubing, then put the tubing into the 90-degree elbow fitting as far as it will go. Slide the nut and ferrule forward and start the nut onto the elbow threads. For flexible braided connection: Secure the nut to the elbow using a 3/8 inch open-ended wrench or adjustable wrench. Do not use Teflon™ tape with compression fittings. (Page 18)