Adding an HDD to my laptop.

I have a Dell Gaming G5 15, and I want to add an HDD. I read that I can add either an HDD or an SSD, but I only see a port for an SSD. I can see the space for an HDD, but there is no mounting bracket. I don’t know where to plug it in or how to mount it, so I’m not sure what to buy. Can you help?