I hope you have all the LDAP info before hand like the LDAP server url, user account and password for ITG servers to lookup users. If you are planning to integrate with a SSL enable LDAP there is more detailed info required.
Then unser sh Kconfig.sh you need to edit Server Conf variable and select the LDAP. There you need to feed the information you have for LDAP parameters into the various server parameters like Auth_Mode, LDAP url, Kintana LDAP Password, Kintana LDAP ID and Base Destination.
You also need to configure the correct LDAPattribute.conf file on PPM server. take the backup for existing LDAPattibute.conf file.
If you are using Microsoft Active Directory, Copy the <PPM_HOME>/integration/ldap/LdapAttribute_AD.conf file to LDAPAttribute.conf file.
If you are using iplanet/SUN One's LDAP server, Copy the <PPM_HOME>/integration/ldap/LdapAttribute_Netscape.conf file to LDAPAttribute.conf file.