Accessing Active Directory Objects via C# (Visual Studio)

private void Form1_Load(object sender, EventArgs e)
{
    DirectoryEntry dir = new DirectoryEntry("LDAP://ou=o,DC=xyz,DC=de");
    DirectorySearcher search = new DirectorySearcher(dir);
    search.Filter = "(&(objectClass=user))"; // (mobile=+44*))";
    search.SearchScope = SearchScope.Subtree;
    SearchResultCollection searchresult = search.FindAll();
    if (searchresult != null)
{
    ???
}