New Computer and I'm So Confused

I just bought a new computer and the setup is super confusing to me. It's a Dell with a "256GB M.2 PCIe NVMe Solid State Drive + 1TB 7200 rpm 3.5" SATA Hard Drive." Apparently, this makes the C drive (OS) 256GB and the D drive (data) 1TB. I installed IT on the C drive before knowing this. Should I uninstall IT from C and re-install it onto D (which requires another activation code from IT - and I've bugged support enough today!)? I've only had to deal with a C drive before, and I only have about 75GB left of my C drive. I'm not computer savvy, obviously. I was able to figure out how to save new content on D instead of C, but this was after I installed IT, Microsoft Office, and my work platform.