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?
From the ‘Website’ dashboard, choose ‘Template - Template Options’
From this menu, you can select the opacity of the header image to adjust the transparency.
The higher the % is, the darker the image will be.
This image is set to 75%
This image is set to 25%
Once a change has been made to this screen, select ‘Save’