Hi,
My name is Igor, I'm Independent Advisor. I have 12 Microsoft MVP awards. It's a pleasure for me to help others and I'll do all my best to help you.
You headset have 5 contact jack. Most PCs use 3-contacts ones so your microphone just is not connected. You need to use 5-to-3+3 contact splitter and connect headset to both headphone and microphone jacks.