"Esc" will change to the command mode.

cursor position h left,   l right,   k up,   j down w forward one word,   b back one word,   e end of word 0  start of current line,   $ end of current line { beginning of current paragraph,   } beginning of next paragraph ctrl-f Forward one screen,   ctrl-b Back one screen :n Move cursor to line number n
editing
a	Enter insert mode, the characters typed in will be inserted after the current cursor position\. A count inserts all the text that had been inserted that many times.
i	Enter insert mode, the characters typed in will be inserted before the current cursor position. A count inserts all the text that had been inserted that many times.
u	undo the last change to the file. Typing u again will re-do the change.
y	yy---> yanks the current line. y5y ---> yank 5 lines y5w ---> yank 5 words
p	Paste the specified buffer after the current cursor position or line. If no buffer is specified (with the " command.) then 'p' uses the general buffer.
x	Delete character under the cursor. 5x ---> deletes 5 characters.
d	dd  deletes the current line. d5d ---> deletes 5 lines. d5w ---> deletes 5 words.
/	Search the file downwards for the string specified after the /.   n-->go to the next word
?	Search the file upwards for the string specified after the ?.
.	To repeat the last modification
:q!	Quit VI without saving changes.
:w	Write out the current file.
:w filename	Write the buffer to the filename specified.
:w >> filename	Append the contents of the buffer to the filename.
:wq	Write the buffer and quit.
:123	Brings you to line 123.
:$	Brings you to last line.
:se number	Shows line-numbers for all lines.
:se nonumber	Shows no linenumbers.
:5,10d	Deletes lines 5 to 10.
:1,$d	Cleans the file.

reference
vi help
vi help2