epotech, it's fairly straightforward process.
Create a "user" object in your Active Directory. For synchronization only, they account doesn't need much privilege in Active Directory.
In your ePO server go to:
MENU > Registered Servers > New Server. The type will be LDAP. In the details section, fill in the blanks as needed.
Lastly create a "Server Task" in ePO to schedule and synchronize with Active Directory.