Query in Access

Ok..I hate using Access compared to PHP/mysql, but it's for school.

In the Access query design screen....
How can I make a query pick only records that have a blank value in a certain field?

Thank you everyone for your help!!

Like:
SELECT
mytable.certainfield1,
mytable.certainfield2,
mytable.certainfield3
WHERE
mytable.certainfield2=Null;

You can use NULL as per above, but sometimes i have had access not recognise a field as Null. The other problem happens when a user enters in a space in the field.

Using a combination of Len & Trim gives you something that will handle those cases.

SELECT
mytable.certainfield1,
mytable.certainfield2,
mytable.certainfield3
WHERE
Len(Trim(mytable.certainfield2))=0;