There are basically 2 scenarios how vSphere Replication can be configured. With separate vCenter Server instances, you need to deploy one Replication Appliance on each site. With a single vCenter Server you will deploy the Replication Appliance on the target site with access to the target datastore. Whatever you are going to do, please ensure you make yourself familiar with the documentation and the limitations. In a single vCenter Server deployment, you may need to do some manual work, if the vCenter Server isn't available at the time you need to recover the replica.
Also, please be aware that replication does not replace backup!
André