Once you have it installed and have the base configuration, changes are you will need to migrate some data off and exsiting system.
LDIF Entries
You will probably not want to enter all your info manually with LDIF, but you will need to add some basic entries into LDAP directory. These prepare the LDAP database for more entires.
LDIF Basic Entries
dn: dc=example,dc=com
objectClass: dcObject
objectClass: organizationalUnit
dc: example
ou: Example Dot Com
dn: cn=admin,dc=example,dc=com
objectClass: simpleSecurityObject
objectClass: organizationalRole
cn: admin
description: LDAP administrator
userPassword: <password>
dn: ou=people,dc=example,dc=com
objectClass: organizationalUnit
ou: people
dn: ou=groups,dc=example,dc=com
objectClass: organizationalUnit
ou: groups
You will most likely already have data you want to add to the LDAP Database. There are conversion tools you can use, and may need to covert to your needs.
Keep in mind what your uses for LDAP. You will need to add atterbutes
dn: uid=fsmith, ou=employees, dc=foobar, dc=com
objectclass: person
objectclass: organizationalPerson
objectclass: inetOrgPerson
objectclass: foobarPerson
uid: fsmith
givenname: Fran
sn: Smith
cn: Fran Smith
cn: Frances Smith
telephonenumber: 510-555-1234
roomnumber: 122G
o: Foobar, Inc.
mailRoutingAddress: fsmith@foobar.com (mailto:fsmith@foobar.com)
mailhost: mail.foobar.com
userpassword: {crypt}3x1231v76T89N
uidnumber: 1234
gidnumber: 1200
homedirectory: /home/fsmith
loginshell: /usr/local/bin/bash
radiusGroupName: mss_systemadmin
radiusGroupName: PSAX_RW
radiusGroupName: Nortel_RO
radiusGroupName: tivoli
radiusGroupName: ciscoworks
radiusGroupName: netscreen_RWA
radiusGroupName: Region_ALL
radiusGroupName: Netview
radiusGroupName: NetviewNative
radiusGroupName: config
Conversion Tools
There are many conversion tools, but these will need to be modified for your environment.