Unlike most word processors you may be used to, vi does not use modifier keys in command sequences. Typically on a PC, you would use some combination of function keys, alt, shift and ctrl. Vi was written to run on a text based system, and so almost entirely uses no modifier keys for commands.
Vi has two operational modes: COMMAND mode and INPUT mode.

When you start vi, you are in COMMAND mode. When you add, insert, replace, or change text, you need to enter INPUT mode. Pressing the ESC (Escape) key at any time, will return you to the command mode. If you are already in command mode, your terminal will simply beep you, telling you so.

For the next several sections, we will be in command mode only. We will learn about the input mode once we know how to navigate around in a file.

Visit for complete manual for VI http://www.cs.fsu.edu/general/vimanual.html