Its very simple. 

Connect Social Media Account -> Click Product to promote -> Add some description -> Make post to selected Social Media Channels. 

1. You first need to connect you social media channels or accounts here; Connect 

2. Click the "Products" menu icon to open the product tab. Then search for the product you want to promote and click on that;

3. Add a post body/description and edit anything you want to suit your audience. 

4. Then, scroll down to select the social media channels you want to make the post to. After you can post immediately to social media or schedule for later