Hi Maricel,
I am agreeing with Thierry comment over your post. Just to add some information. The HR data replication happen through HRMD_ABA idoc only and the mapping is created once it replicated to CRM. You can replicate employee by by PFAL transaction in ERP side. You need to have HRMD_ABA message active and also related partner profile which you can see in WE20 transaction in ERP side.
thanks