Search Form Troubles

Hi all - It's been years since I did anything in access. I'm trying to develop a membership database, and among other things, I want the app to launch with a search screen. I have 3 fields on the screen:
1. surname
2. firstname
3. childname

I want the user to enter anything (even partial info) in any of these fields, and when they hit the search button, a listbox - (best choice?) will display all records that match on any inputted info. If nothing is entered, and the search button is hit, I want all records in the members table to be displayed. I expect the query to be something like this:

if not isnull (surname field and firstname field and childname field) then

select surname, firstname, childname
from members
where surname like [txt_surname] or firstname like [txt_first_name] or childname like [txt_child_name]

else select surname, firstname, childname
from members
endif

What I do not know is HOW to implement this through MS ACCESS 2003.

Any help would be greatly appreciated.

Thanks.