You won't be able to see the linux files in windows without special software.
When you boot your computer, are you presented with a GRUB menu to select your desired operating system?. If you don't have that, then Mint did not install fully. Try reinstalling, and watch for errors with the installer.
When you reboot with the pendrive, you should see a list of options to boot. Select the "Verify Disk" or whatever it is called. If it has errors, you will need to recreate the install medium. You might also have to re-download the Linux Mint 13 ISO. You can check the MD5 hash of your downloaded ISO against the one on the download page on the website. If they are different, you will have to re-download the ISO.
Running on a 4-slot toaster @ 60Hz