1. Download Linux Mint (64-bit w/ Cinnamon desktop) iso file https://www.linuxmint.com/download.php

2. Install UNetBootin for Windows http://unetbootin.github.io/

3. Connect a clean 2GB or greater usb flash drive

4. Install Linux on the flash drive. In UNetBootin, select your downloaded Diskimage and USB drive and click OK

5. Reboot your PC from USB drive

How you do this depends on the PC, but a message usually comes up during the restart
about which key to press to redirect to the Boot Menu (F12 on my PC).

If that is not an option, you should be given an key to hold to get into the BIOS (Del key on my PC).
In the BIOS, you can change the boot order so that the USB takes precedence over the hard drive.