Microphone and Audio cant work at the same time

[joerobert2000]

Trying to use a brand new plantronics 300 Rig gaming headset but i cant get my mic and audio to work at the same time, the headset comes with one single 3.5mm jack for the device, but my pc has two seperate 3.5mm jack intakes for the mic and audio separately. Am i just being dumb, or is there no way around this besides either getting a different headset/ a splitter?

 

[Nutroll]

You'll need a splitter I do believe, are you sure it didn't come with one?