Just received my profits from a "watch only" address, where do I obtain private keys?
If your profits were sent to a watch only address then you are in trouble.
Ordinarily, a private key is created first and then the address is created from that private key.
Your wallet makes new private keys for new addresses.
Please contact the person who gave you the watch only address.
If you do get the private keys then you should immediately move any bitcoin to a new address where only you own the private keys and nobody else knows them, so that the bitcoin cannot be taken.
An address or pubkey script stored in the wallet without the corresponding private key, allowing the wallet to watch for outputs but not spend them.