Each plan has a place to add a plan title and series name if your church uses those. These items are shown on your main Plans page as well as in each individual plan.
Check out this clip from Planning Center University.
To add a title to a plan, click the Actions drop-down in the upper left to expose this field. You can then add your title in the Plan Title field. Click out of the field to save.
To add a series to a plan, click on the Action dropdown in the upper left, and select Add Series.
Choose an existing series to add the plan to, or type in a new series name, and click Create a new series.
Hover over the No series art box and click Add.
After the image is uploaded, click Submit to add the art to the plan.
To edit the series art or title, click the image within a plan to make your changes.
Make changes to the series art or title, or remove the plan from the series.
Hover over the image to replace or remove it.
Update the series title. You'll have the option to change the title for the whole series or create a new series.
Remove this plan from the series.
Click Submit to save your changes.