You can give your customers the opportunity to share their purchase with social media when they make a successful order. This can be done via Facebook and Twitter.
You can set this at: "Starting point > My Webshop > Settings > Social media > Share purchase via Social Media".
You have 2 settings options here:
1) Share purchase on or off.
2) Default text for Twitter (it is therefore not possible for your customer to choose the text theirself at this time).