The instructions provided by "Concrete" are complete. Just follow the directions and remember:
You must first use the hand-held transmitter that came with your opener, by pressing the button you want on homelink and the transmitter button at the same time. Ensure handheld transmitter is 3-6 inches away from your homelink button. Then, go into your garage, locate the "learn" or "train" button on your garage door opener (may need a ladder and with Chamberlain, I think its on the right-hand side of the opener as you're looking at it standing at your garagae door looking into your garage...), punch the learn button (a light (LED) will light up) and within 30 seconds, go back to your car and push the same button on homelink that you just pushed in the previous step and hold for 2 seconds, release, then push it again for 2 seconds and release. That should do it. I hope this helps.
Recently sold my beautiful 2006 300C AWD.