You only get access to ANY sparrows once you've reached a certain point in the game.. It's not nearly as early on as it was in Destiny 1.. So you'll only have this turn up for collection (I'm assuming at the 'postmaster' or a similar vendor) this once you've acquired another..
You earn a sparrow in-game either by completing the campaign or by getting one in a Bright Engram loot drop after you've got to level 20..
Changing the title of the thread makes it sound like I haven't redeemed the code or unlocked sparrows in game. I have. I have already got a couple of sparrows. But where do you get the virgin one. Is it mailed to you or is it claimed from a vendor. Very annoying.