i have an '01 toyota sienna..and i'm wondering how to program the built in garage opener..i've tried the manual for my garage opener..but that didnt work..anyone know how to do it?

Both the prior posts are correct. But...After you have programmed it as was explained, test it by pushing the car's button. If it flashes very quickly, then you have a rolling code type remote, and you will have to climb a ladder to your garage door opener, and you will need a helper to push the button. Look at or acquire a manual for your garage door opener, and it will explain how to do it.

I assume your sienna has "homelink" if it does, its very easy, hold your remote very close to the home link buttons, push the buttons on remote and homelink at the same time, hold until light flashes from slow to fast, this could take a minute or so.

Check the manual that came with the car. If it doesn't say it there, you can probably call your local Toyota dealer and have them explain it to you.