How do I get a filtered collection of MembershipUsers from a data store using custom profile properties?

A portion of my web.config file:
 
<profile enabled="true" defaultProvider="AspNetSqlProfileProvider">
      <properties>
        <add name="FirstName" type="System.String" />
        <add name="LastName" type="System.String" />
        <add name="Age" type="System.Byte" />
        <add name="Weight" type="System.Byte" />
        <add name="City" type="System.String" />
        <add name="State" type="System.Byte" />
        <add name="RelationshipStatus" type= ...