I am even newer than you, gorsefore, and have downloaded the Instructions and found this re md5sum:
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If you happen to run Windows, chances are you don’t have md5sum installed. You can
get it from here: http://www.etree.org/md5com.html
Place the ISO file and the md5sum.exe in the same place (let’s say in C:\) and run
“cmd.exe”. In the command line environment, type the following commands:
Then compare the signature to the one present on the website.
= = = = =
I didn't even know that 'cd' stood for Change Directory
Got there in the end via:
In Windows Explorer, copied md5sum.exe and the LinuxMint download into C: root directory. Then (the bold characters are what I actually typed) Start/Run/cmd.exe
Waited and waited, then got ad399a6bd452ee88f7464bb5259c417e *LinuxMint-4.0.iso
but there aren't any signature numbers on the Mint download page, not that I can see
I burnt the CD at x4, it displays nicely so I wouldn't have thought it was corrupted.