You either need to write code behind your command button to write the data
from the boxes on your form into your table, or make sure the control source
property of the form is set to your table name in which case the data will go
into your table without the need of a save button.

You need to set the record source of the form to be the table.  to do this,
open the form in design view and open the properties window by right clicking
the little square in the top left hand corner of the form and selecting
properties from the menu that appears.  The properties window will open and
you need to click the Data tab.  The top text box is the record source.  When
you click in it, a dropdown arrow and a set of elipses will appear to the
right.  Click the dropdown arrow.  A list of all your tables and queries will
appear.  Choose the table you want from that list.  Save your changes by
typing CTRL+S and open the form normally.  Things ought to work like you
expect them to now.  However, you won't need the save button.  You will be
directly entering data into the table via the form and when you move to a new
record, the old one will be saved.

HTH

Mike