Auxiliary input for Stock Stereo

[Derek Gabutin 0]

Hi, i would like to ask on where can i place the aux in this stock stereo of chevy spark. A friend of mine gave this to me about a year ago and he said he didn't remember where the auxiliary connection was to be connected. The stereo is already placed now on my car yet it works but without the aux input. I would like to try and know if anybody has an idea on how will i connect it.

 

For the pins, it seems we have found connections for the power, speaker and light input at the back yet on the right side i cant seem to find any data on what should be connected. 

 

Can someone please help me :( Connecting my auxiliary to an fm transmitter really gets the quality bad :(