Select the card that you want to create a campaign for:
Since you have not created a campaign yet, select the “Green plus”:
Follow the prompts and type in details of the campaign that only you can see:
After selecting the “Green check mark” at the top right corner, you will have the following options:
After selecting how you would like to post your campaign, you will return to this screen. Just select Done.
The campaign that you created gets added to your campaigns list under your card.
See this in action: