How can I learn about the software for early Bitcoin Miners?

I had lunch with an older man in town, and I mentioned that I'm into crypto. This sparked a conversation, and eventually he told me that he mined Bitcoin the in the very early days. He said he wasn't tech savvy, but he followed internet instructions back in the day and set up his computer to mine Bitcoin. None of it made sense to him, saying that he felt like a computer genius with all these terminal numbers moving around on screen.

Long story short, he lost his keys, or really just didn't understand it enough to know what it is and his wife made him quit. So I went to his house and he sent me his old computer and USB key and told me that if I could figure it out, we can figure out some share as it's better than just losing it.

I have not plugged in the computer yet. Before I do, I want to research any instructionals about how to navigate my way through any early Bitcoin software. How can I find this? Thanks