How to sync only certain songs?

I just brought my new iPhone 4 home, and started syncing it. To my chagrin, I realized that I have more music than the 16GB can fit. So, I unchecked all of the tracks that I don't really listen to. Unfortunately, I can't figure out where to tell the phone to only sync the tracks that are selected. I remember this used to be pretty easy. Please let me know, I would appreciate your help.

Otherwise, it's a pretty fun toy.

That's a pretty clunky solution, unfortunately. There must be a better way... Right? Thanks for the quick reply, friend.

That is the fabled button I'm looking for, but it isn't under the "Music" tab in the phone, or any other tab for that matter.

Oh wow, I didn't even notice the scroll bar on the summary page. Thanks for the tips, have a good night. Now, I just have to shave off 500 songs... I wish that problem was as easily solved!