How do you use AP tuner with Electric Guitar?

I bought the adapter(1/4" to 1/8") and connected my guitar to the mic-in port of my PC. But AP tuner is not picking up the strings sound. It is picking up the sound of volume knob when I increase the sound(which is quite strange in itself) but not the strings.

I tried many other tuning software both online and offline but nothing there too. Can anyone help me out?

I also tried recording with MS Sound Recorder and I can hear only faint guitar sound while listening to the recording.

P.S.: I am keeping the volume down, not increasing it more than a quarter, cause I heard somewhere that it can kill the sound card as the card is really sensitive. I hope that is not the reason behind this.