Call Sears' corporate offices for customer service. Tell them you want a manual sent to you.
To be clear on terms: opener = the mounted, motor unit attached to the door. controller = the mobile unit that's in your car.
On some garage door openers, the control has to "learn" the frequency for the opener. (If this is the case...) the opener will have a little button on the back of it that you push - and probably a little light right next to the button that will start to blink. Then, you push the button on the controller. The light will stop blinking and now the controller should work.