Well I'm no expert on electrical engineering-- not yet anyways

-- but from the pics it does not look like its turned on. Lol it just looks like the usb thing is. If it is turned on then id suggest making sure the gain knob on the chanel youre using is about mid way (12 o clock) Then make sure the faders are up (which is what it looks like)
Mixers are different but you need to make sure that the tape/coax output is not muted. Make sure all of the little black buttons are not pressed down, (the mute ones)
If nothing works then you should try making sure that all knobs are turned half way up. My first guess is that the "CD/TAPE" button is muted. I'm not familiar with this mixer though.
If the meters are jumping up and down keep them at a decent volume and make sure that youre computer sound through the usb thing and also make sure that your speakers are plugged in correctly. It does not look like youre speakers are plugged in because the output on the USB thing is plugged into the mixer but the output on the mixer is going straight back to the USB interface
That usb interface appears to run as your sound card meaning the output on that usb needs to get to your speakers. This is unless youre only using this thing as a recorder and not to replay sound. if it is used as this make sure that its not set as youre default sound device. On windows you just go to control panel then sounds and devices and make sure its not the default. When you do this you will have to make sure that the audio software you are using uses the usb interface as your recording device rather than the windows default.
If nothin works.
Welcome to the world of recording you have learned your first lesson.
The harsh lesson of Behringer.