The ratios can be seen with this gear calculator Bicycle Gear Calculator in the drop down boxes they have the cassette for this bike and then under the display drop down select speed and it will give you the speeds for each combination. If you know how fast you typically ride on the various types of terrain, this will give you a good idea if your gearing is too high or too low relative to your needs.

The bike pictured has Sram road shifters on it, in order to shifter to a higher gear, smaller cog you push the lever to the left with a short push. To shift to a lower gear, larger cog you push the same lever but give it a longer push/throw.