Headset mic not working

[mave_estrella]

When I speak with someone on Skype, the other party hears me ok but when I tap on the mic mouthpiece, she doesn't hear me so apparently my headset mic is not connected. How to configure the headset mic? My laptop has two ports. I was advised to buy a sound card. Will it work? (Laptop does not recognize my headset)

 

[helpstar]

So, the mic is working and than you tap and the voice of yours is gone for the other party/her?