Got solution with username and password for directyentry.
static DirectoryEntry DirectEntry(string ou)
{
string ldapname = "sharepointtest";
string name = "h.com.sa" + @"\" + ldapname;
DirectoryEntry ldapConnection = new DirectoryEntry("rch");
ldapConnection.Path = "LDAP://OU=CEO,OU=ORGANIZATION CHART,DC=h,DC=com";
ldapConnection.Username = name;
ldapConnection.Password = "123";
return ldapConnection;
}