all homelinks work the same, as far as I know. It is your garage door opener that may be different. But, I believe there are 2 ways to do it. Try pushing the button on the back of your garage door opener by the LED. The light will begin flashing for 30 seconds. During this time, it is accepting new signals. So you have to quickly get in your car and push and hold the button you want to work your door. If the opener accepts the signal, it will flash its floodlight. Then just push the homelink button again to see if it raises/lowers the door.
The second way I don't remember quite so well, but I believe you hold the corresponding button on the homelink until THAT starts flashing, then point your remote at it and push that button. The homelink will flash 3 times quickly if it accepts it. I don't think I've ever gotten this method to work, which is why I'm unsure of the procedure.
I've had new and used cars with and without manuals and the first procedure has always worked. It may take a couple of tries, though.