The best way to understand these concepts is to actually fire up vi and edit a file. In the example ``screens'' below, we're only going to show a few lines of text, as if the screen was only six lines high (instead of twenty-four).
The syntax for vi is
vi 
where 
is the name of the file that you wish to edit.
Start up vi by typing
/home/larry# vi test
which will edit the file test. You should see something like
The column of ``~'' characters indicates that you are the end of the file.