This is a good question. I've read the whitepaper so I'm able to answer it to the best of my knowledge. Think of Social Wallet as a platform that connects through social media. When you send tokens to your friend on facebook you must send them from your wallet (this means you need to make a social wallet account first). Your friend receives a link in PM on Facebook. They click on the link and collect their tokens (they must also make an account / wallet with social wallet) then after they click accept the tokens move from Social Wallet into your friend's wallet. So the transaction looks like this...

You send from your wallet to friend's social media through Social Wallet -> Social Wallet holds the tokens until your friend accepts them -> Friend gets PM, clicks on link, makes account and accepts WIRE -> Friend's Wallet.