Where can I find campaign_activity_id

Hello team,

I'm testing Send Email test through this url: 

https://v3.developer.constantcontact.com/api_reference/index.html#!/Email_Scheduling/testSendCampaignActivityUsingPOST

Asking campaign_activity_id there. But I didn't campaign_activity_id.

Help me to find campaign_activity_id.

Thanks,

Samuel