Snapchat privacy settings

To report an abusive Snap on Snapchat.
After viewing the Snap press and hold on that Snapchatter's name to bring up their profile. 
Select the Settings cog icon.
Select 'Report'.

To report a Story on an Apple device.
Select the content.
Select the Three dot menu.
Select the flag icon in the bottom left corner.
Choose the best option to report.

To report a Story on an Android device.
Select the content.
Tap and hold the content.
Select the flag icon in the bottom left corner.
Choose the best option to report.