Todd wants to know how to backup personal files on his work PC. Ideally, if there's an IT department, they'll have their own backup system to use. Or a managed service provider (MSP), who may have a set way to do it. But if not, it's on you to backup your data. To make a copy of things to work on at home, a good Thumb drive or portable external hard drive could do the job. But your IT policy may disable the USB ports as a security measure. Assuming you still have access and are allowed to, then a small USB drive is ideal. Leo likes the Samsung T7 Portable drive. $129 for 1TB. There's also the Western Digital Amourlock Drive. The great thing about that one is, it's locked until you unlock it with your phone. Good security feature.
You can also use Second Copy as backup software, IT permitting, which will watch and backup when you plug the drive in for backup.