In general, if connection is to be made via the LDAP tab, then your Network Administrator or DBA should supply this file. This file needs to be placed in the %ORACLEHOME%\Network\Admin folder or the TNS_ADMIN location.
While Toad does have an LDAP Editor on the Connection window, the ldap.ora file should already exist and be in the correct location. Please refer to Oracle documentation, or request assistance from Oracle Support in regards to creation of an ldap.ora file.
