Hmm looks like duplicate effort for people who have given biometrics recently and got their picture taken.Hi, they don't use the same photo from Biometrics for the PR card.
When approved (this is what I found out from all of these forums here), you will receive instructions to send a copy of that "Letter" or copy of COPR with a photo. At the back of that photo should be stamped date and location and you also have to write your name and date of birth.
Don't worry, the instruction letter you will receive will have full details of what to send, how to send, how many and where.