Vim is my favorite editor. Here's the basics, just what you need to know to use vi/vim.
h - left
j - down
k - up
l - right
<CTRL> d - page down
<CTRL> u - page up
gg - top of page
G - bottom of page
^ - beginning of line
$ - end of line
u - undo
<CTRL> r - redo
. - repeats last thing you just did
x - deletes current char
X - backspace chars
dd - deletes line
D or d$ - delete to end of line
i - start inserting
I - insert at beginning of line
A - insert at end of line
o - insert new line below
O - insert new line above
s - replace current char, and insert
cw - replace current word, and insert
S or cc - replace current line, and insert
C - replace to end of line, and insert
r - replace one char
R - replace all chars
p - paste at cursor (or below)
P - paste above line
yy - copy a line
yw - copy a word
v - begin visual block
V - select full line
<CTRL> v - begin a block