There's a good general introduction at: http://www.linuxcommand.org/learning_the_shell.php
More info. can be found through: http://www.howtoforge.com/
You can also try the Linux Mint Wiki - access via the header of the Linux Mint Firefox screen.
It's a good idea to subscribe to these - I keep a text file (with a link to Desktop) into which I enter all my Usernames and Passwords. Of course this doesn't include banking items!
I'm still a Newbie but have been greatly helped by advice via the forums - mainly Linux Mint, but also sometimes
Mozilla and even Windows BBS and HelpWithWindows. It's a matter of gradually finding your way around - I have a long list of URLs entered as Info sources in my Firefox Bookmarks.