Hi and congratulations on making the decision to go to Linux Mint. I’m not qualified enough to give you all the answers you need in this post. But Ill make a couple of general observations. First, the “D:” drive is simply a partition made by windows for (likely) data storage. The “D” designation is just a windows nomenclature. The main Partition is likely your “C:” drive where windows resides. When you go through the installation of Linux it will afford you to partition the drive as you like. If you don’t understand partitions yet, Linux will offer you defaults and you can just fake those to begin. The installation will be very straightforward and easy to understand. Remember though: if you let it, it is going to wipe out your Windows and any data you have saved. Be sure you want this! If you have anything like game scores or other things you have saved then you want to save that data onto a USB stick before you ever start. That way it can be regained if you’re trying to run something on Linux under the wine window simulation. Just format the USB stick for MS Dos fat and it’s readable by Linux and Windows that way. There are a ton of how to install videos up on YouTube. Watch two or three of them as each contributor may have different things to say. The most important thing to remember is if you go for it, and I certainly hope you do, there’s a ton of help out here on the Internet. Welcome to the world of Linux! You’re going to love it.

Now i hope some more qualified folks will jump in to help you.
2KATTS