I dont think you understand how it works.
Unlike windows Linux has a Live DVD ( the Live DVD or USB is also the Setup DVD/USB ). The iso file you download has built in Live mode. ( if you burn a dvd or put it on flash it doesnt matter ) when you boot from DVD or from flash it will boot into "Live mode". that is how linux is. it allows you to preview the operating system before you install it. Most linux's are like that. Windows boots straight into setup. linux doesnt. it first boots into "live mode" where you can actualy see the operating system before you install it.
once inside live mode there is a install shortcut on desktop. when you run that it will bring up the setup installer. and after that it will ask if you want to install "along side windows" ( meaning you keep windows and run linux as well ) or if you want to "replace windows" in which case it will format your hard drive and install just linuxmint. follow the setup instructions and fill out username and password and stuff...
after the whole setup is done, it will tell you to reboot and remove usb. so you click reboot and wait for it to tell you to remove usb, when it says so remove it and hit enter, then the computer will boot into linux on your hard drive.
you can then format your flash drive and use it for other stuff, linux is now in your PC.
its very easy and simple to do.