Unfortunately the opacity feature is not yet available in Funnel.com, containers may only be transparent, have a solid background color or an image background.
To apply a translucent background (semi-transparent), you can use a third party photo editor such as Photoshop to to create a translucent image.
1. Open a new file
2. Click on the shape / rectangle tool
3. Create a shape
4. Adjust the color of the shape by double clicking the image on the Layers tab (make sure that the shape layer is selected)
5. Adjust the opacity on the Layers tab (make sure that the shape layer is selected)
6. Click on File > Save As
7. Save the file as png
1. Select the container
2. On the sidebar, click choose on Background Image
3. Upload the png file from Photoshop