When lubricating your garage door opener find out what type of opener you have. There are 3 basic types of openers. Chain drive, screw drive, and finally belt drive. Lets start in that order. Unplug your garage door opener. You will need to have a low temp grease called lubriplate. Look for a nylon gear inside unit and coat liberally on both gears. Next you might want to tighten chain due to it stretching over time. You can also lube the chain with a light duty spray lube. That covers the chain drive.
Screw drive openers really only require the actual rail to be lubed. Again using the lubriplate low temp grease get a remote control in one hand and in the other hand the grease. Take remote and activate door. When the screw starts to turn run the grease along the turning portion of the rail until you have gone the entire length. You will hear an immediate difference and you will know that you have done it correctly