Carin
Give it a try.
Just goto the existing table, right click and select Design View.
Now at the bottom of the list add a new one, let's call it Terminated.
Set it's Data Type to Yes/No.
Now when you view the table you'll have a field where you can indicate if the record is for an employee has been terminated.
Note the field will probably show as a tickbox.
And you should try this on a copy of the original table before proceeding further.
As for a query just goto the Query window, select New Query, double click the * in the list of fields.
Then drag the Terminated field to the query grid and then close the field list box.
Now you can set the criteria as you want - Yes for terminated records, No for non-terminated records.
Note like James I don't have Access 2007, tried it but didn't like it, but these are the basic steps for this sort of thing.
And hopefully Microsoft hasn't changed things too much.