Speaking as a total dunce here.
If I install Mint will the programs I already have on my Windows 8.1 just go up and run or do I have to do something to get things like Skype, Audacity and Adobe to work. Do I have to uninstall 8.1 eventually? Will all my files be there or do I have to remove them and reinstall?
I wish I had a spare computer to learn on, but I only have this one and I'm sunk if I mess it up.
I assume I should back up everything to an external drive just in case...
Get yourself a USB thumb drive. For 64GB you can get one for about $15. Great to backup your files to.
Linux has free software for most things. Your Windows programs don't run directly on Linux. There is Skype, Audacity and Adobe for Linux.
There is something free from Oracle called VirtualBox. You run this on Linux and you can then install any Windows operating system on a virtual drive within Linux, if you need your Windows for any reason.
If you already have Windows 8 then your machine is probably 64bit, so download for 64 bit.
I run the Xcfe desktop version because I am not into the bells and whistles, but you may just want to try the Live Cinnamon version and see how it is first.