This article explains how to share photos and videos on Snapchat on iOS and Android devices.
How to Save Photos and Videos on Snapchat
Snapchat Memories lets you save snaps you take within the Snapchat app as well as upload existing photos/videos from your device. Here's how to easily access the Memories feature in Snapchat:
Open the Snapchat app and go to the camera tab (if you're not already there) by swiping left or right through the tabs.
Tap the small double image icon that appears directly below the camera button.