This article is related to PromoteMyPlace Version 2 only. Not sure which version of the application you're using? See Which version of PromoteMyPlace am I using?
When you have an image on your page, you can add a caption below it
To add an caption, select ‘Basic Elements’ from the top menu
A side menu will appear, select ‘Caption’ from there
Drag the caption into the required position
Once you drop the caption, you can update the text by double clicking in the caption box