Headphones won't fit in laptop headphone jack?

I bought a new laptop Lenovo Ideapad 310 but when i try to plug in my headphone with a 3.5mm jack it won't go in completely. How can i fix this or is this the computers fault?

It is your fault. The headphones plug is not designed for that socket. See the symbol next to the hole? It has a headphone with a little dangle below the earpieces. Microphone. That socket is all-in-one for headsets. That includes a microphone. You don't have that.
You need an adapter. It has one plug and two sockets. NOT A SPLITTER! It is marked or colored for headphone/speaker and microphone. Go buy one.

What type of adaptor would I need for this please.