Just want to mention that "C:" is a Windows-specific convention for identifying hard disks. Linux doesn’t have quite any concept of a “C:\ drive.” You’ll of course still have your OS installed on the same disk that today Windows calls "C:", but on Linux it’ll be (and I’m oversimplifying a little bit here) “/”.
I’m a little bit jealous because I can’t start learning such things for the first time like you will be soon. Ha!
My advice: don’t feel like you have to learn it all at once. Don’t feel bad about just accepting the defaults that the installer suggests where you don’t know what to do otherwise. If the command line intimidates you (we were all there once) use the gui tools exclusively as much as you like. Some day you might start to feel limited sticking with gui tools. (Or maybe for your particular purposes, the guis will always be perfect.) Until you do start to feel like you want to learn more about such things for your own sake, don’t let anyone tell you you’re doing it wrong by using the easy way.
(This from someone who does basically everything from the terminal. Lol!)
And don’t be too afraid to break things. Breaking things is arguably the best way to learn. And do feel free to reach out to friendly communities for help when you need it. It’s likely that if something has gone wrong (which is pretty unlikely with Mint), you’ll need to do some terminal stuff to fix it, but people can help you out with that if you ask. :)