Here is what i would recommend. First find a distro of Linux like Ubuntu, or Fedora, or one that looks appealing to you. Then install it on your computer. After you do that, open a terminal and play around with the commands. Also, you can read the man pages. These are a set of pages that act as a manual.
As for a document to read that has linux commands there are any number of them out there. Just do a google search. Here is one that I really like. O'Reilly Commands.
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