You don't sound dumb at all; if anything, you're being smart as well as careful by asking all these questions. And you should see the kinds of messages I wrote when I was about to do this myself, having no idea what the process looked like. (I was extremely lucky to have the help of someone who was quite knowledgeable and also very patient with me.) But the process is so straightforward, when I did it a second time for my mom, I didn't even have to look up directions.
Bootcamp Assistant is in Applications\Utilities. Right-click (or crtl-click) on its icon and select Get Info. Under General, you'll see its version listed. I don't know which one you have, but when you find out, you can google whether it's compatible with Windows 10, or else post it here and I'll see if I can figure it out. Mine is 6.1.0, by the way, which supports 10 only.
Once you have that question answered, then you can narrow down the choices about how to get Windows onto your computer. It's also a good idea to find out which version your dad is running, so you can plan now.
