From your main dashboard you can click the 3 vertical dots to make changes to your campaign.

You can Pay, Edit, Copy or Delete a draft campaign from your main dashboard.

If you're in a specific campaign you can make changes by clicking the 3 vertical dots on the top far right of the campaign as seen below.

When creating a new campaign or editing a draft you can Save and Exit at the bottom left of your screen. This will save your progress and you can come back and make further changes as required. Alternatively you can also delete the draft campaign.

You can move through the campaign by clicking back or next. At the review page you'll have the option to "Add to cart" or "Checkout" the campaign.