First way - Select a Collection in the Search Collection box. Use the drop-down menu to find your Collection, or begin typing in its title.
After selecting the collection, the SHARE button to the right of the title of the Collection will become active. Click the SHARE button to share this collection.
A Second Way - select "view my collections" in the drop-down menu in the Search Collection box. A page showing all your collections is displayed. Find your collection, and click the SHARE icon in the thumbnail image representing your collection.
In the Search Collection