There are many ways to share!
Go to your main shop page and below your profile is a share option. Tap on this and you will notice the different share options and you can choose the appropriate one.
You can also share specific listings by going to the listing and to the right of the favorite button is a box with an up arrow (In Android, the share icon is three connected dots). Tap on this and choose "Share this Item" which will bring up the sharing options.
*Note that at this time in iOS you are not able to share your own listings to your followers*