When you open a form in Access 2007, there is a Search box in the horizontal
scrollbar (beside the navigation buttons.)
Or, you can right-click on the County field, and filter to a particular
field.
If you want something more than that, there's a utility you can copy here:
Find as you type - Filter forms with each keystroke
at:
http://allenbrowne.com/AppFindAsUType.html
It consists of a combo box (for selecting which field to search), and a text
box (for typing the value to find) that you copy into your database and use
on your forms. The code is copy'n'paste.
Alternatively, here's a more powerful one:
Search form - Handle many optional criteria
at:
http://allenbrowne.com/ser-62.html
This one illustrates how to create several search boxes, and write the code
to find only the records that match whatever criteria the user chose in the
various boxes.
