Action Details
Requirements and how-to articles for Snapchat's action:

After you create a snap, you can send it to friends, a Group, add it to your Story or send it to the world using "Our Story."

You need this to get it done:

iOS or Android Mobile Device
A mobile device compatible with the official Snapchat app is required in order to create and send Snaps.
Photo Snap
When in camera mode, tap the camera button to take a photo Snap.
Video Snap
When in camera mode, press and hold the camera button to record a video Snap (up to 10 seconds long.)
Caption (optional)
You can add a short caption to your snap.
Sticker (optional)
You can decorate your snap with stickers.
Send Snap
Choose where to send your snap.
Save to Memories (optional)
If you want to keep your Snap to use later in a Story or a Flashback Memory, make sure to save it to your Memories before sending it.
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How-To Articles
A list of useful links for you:

Snapchat Support - Send a Snap
Official guide on how to send a Snap.
Link missing here or found errors? Improve How-Tos