Aurora-R7, upgrade HDD, options?

So I just bought a Aurora-R7 directly from Dell and my HD is only 265GB (like, 3-4 games can fill that up). This is my current HD = 400-AVIX - 256GB M.2 PCIe Solid State Drive

So I am looking to buy a new HDD, but I have no idea how to plug it in. Is there a tutorial or help somehow on how to to this? What pieces I will need etc? I don't even know if its possible to do it, how can I check? I am very upset about this. I haven't took a real look at the HDD capacity when buying (to be honest I was definitely not expecting a 256GB HDD. It's 2018.