If pico is not on the machine, nano (a clone of pico) or joe might be. Both are easier to use.

However, still try to learn vi to the point of usability, in case none are available.

I remember the following for vi:

Arrow keys navigate
i changes to insert mode to type where the cursor is
Esc backs out of the insert mode
x when not in insert mode deletes the character under the cursor
dd deletes a line
:w writes the file to disk, :q quits, :q! quits without saving