You have to restore your database on the standby server and create a standby crontrolfile. To do that using RMAN you will have to :
Make rman backup available on standby node
Create init.ora for the standby database
Restore controlfile from the backup on standby server
Mount restored controlfile
Restore the backup
Replace restored controlfile with standby controlfile generated on primary catabase
Start applying archived redo logs.
These are not step by step instructions, but more high level steps.
Hope it helps
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