current active directory search filter

Here's my current Active Directory search filter:

        deSearch.Filter = "(&(objectClass=user))";

h开发者_StackOverflow中文版ow do I modify it to find a particular user/users in active directory? For example, how do I search for

first names that begin with San*?

I'm no expert but try

(&(objectClass=user)(givenName=San*))