Dear All,
At some pint of time during your CLI adventures with GNU/Linux, you'll need to use an editor for sure. So in your free time (when you are not preparing for exams), make it a point to go through a vi guide [1] and use the attached cheat-sheet (pdf) as reference. Also read the vi manual entry by doing 'man vi' on the shell. I hope you'll get well versed with vi by the next class. Best of Luck for exams.
[1] http://acms.ucsd.edu/info/vi_tutorial.shtml
Thanks
Suchakra