Shifting combination shift/brake levers

Harder to describe than to do, that's for sure.
You need to say what model of shifters you have.
On the Sora's you push the larger brake lever inward to shift to a larger sprocket or chainring, and you down shift (to the smaller sprocket or chainring) by pressing the smaller thumb lever.
Someone who drives an Ultegra or Dura-Ace will have to tell you how to work those. Or check Shimano.com.

For Ultegra and Dura-Ace push the brake lever inward to shift to a larger cog or chain ring, and push the small lever behind it inward to shift down.

sugbug said:

I'm borrowing a Cannondale R500 from a friend who left the country last week and didn't realize until I rode today that I have no idea how to shift the Shimano dual control levers. I feel really stupid. Can anyone help?

Brake lever pushed towards the head tube shifts one way, and the lever behind the brake lever shifts the other.

When buying a bike ergopower works better - wider range of changes, can brake and shift at the same time with complete control, and requires a lot less maintenance (10 000 miles per set of cables through a British winter (very wet with salt and grit) and summer (wet) than Shimano. Whole system is also user servicable if you have a bit of patience. And finally the profits go to Europe and not the far east.
😉