You should first dual-boot. It means you will keep your Windows partition and when you turn on your computer, you can choose Windows or Linux to boot up.

To choose a distro, there are plenty of YouTube reviews. I'd recommend Ubuntu, Pop!_OS or Linux Mint for a beginner. Dual-booting is easy on these distros, you just have to select install alongside Windows and then how big you want the Linux partiton to be.

For putting on a USB, download the ISO of your chosen distro, and use BalenaEtcher to flash to your USB (it will erase everything from your USB, so back your data up). To boot into the USB, reboot while holding press Escape, and see if that brings up a boot device picker. If it doesn't, try other keys at the top of your keyboard or press the restart button in Windows 8+ while holding down Shift, wait for it to load, and in the blue menu, ho into Select boot device (or whatever it's called) and select the USB.

Before installing, you should check out if stuff works on Linux like audio (you can test these out because you are on a live system booted from your USB), and if it doesn't, check if you find a fix online, but everything should work fine.

For the software alternatives (if they aren't on Linux), I recommend alternative.to, and learn the new apps. When you feel comfortable, you can then move all your files to Linux and completely delete Windows (you should BTW be able to see your Windows partition from a files app).