How to program wireless garage door openers?

I have 2 wireless number pads for garage door openers... I cannot get them programed.
One is a Chamberlin and the other is a Sears.
Help!

If you keep the remote in hand and press on the back of the garage door opener (button)you should have a blinking light
then press on your remote as you stand in front of the garage door opener. You may have to try it more than once but it should work. I did this a few months ago.

I tried to write before but my answer doesn't appear. Keep your remote with you and first get on a small step ladder so you can push the 'red' button on the back of the garage door opener. You will see it blink. Next step in front of the opener and point the remote to it. It may take a couple of tries. I did this with a chamberlain a few months ago. Sears is same as chamberlain so it should be the same procedure with both. Hope I helped.

Previous answers are right on. I also found that the folks who sell the garage door openers do not want to come out on 'frivious' things like this and are willing to walk one through it on the phone. At least that my experience.