Polo theme offers a wide range of row background variations - background color, background image or video backgrounds. We will dwell more detailed on each of them in this topic. In order to configure row settings of a particular row on the page, first of all click on the PENCIL button in the upper right corner of the row section. There will open Row settings window with all options in it.
Open Row Settings and switch to Design Options tab. Select background color with the colorpicker or upload image by clicking on the PLUS image.
If you upload an image you can choose its background size in the dropdown list below. 
Go back to General tab to choose one of the available Row stretch options to make your background fullwidth.
Open Row Settings, staying in General tab scroll down to Parallax section and select Simple or With Fade option from the dropdown list. Upload an image from your computer or select one from Media library. Set Parallax speed or keep value by default. After that make your row fullwidth in Row stretch section.
Open Row Settings, staying in General tab scroll down to Use video background? section and check YES checkbox. Insert your Youtube video link in YouTube link field. After that make your row fullwidth in Row stretch section.
Open Row Settings, switch to Video background tab, check Enable video background with self-hosted video checkbox and insert video links in MP4 and WEBM/OGG formats, that you have previously uploaded to Media library. If needed check Mute video and Loop video checkboxes too.
It is also recommended to upload a Video poster image. Since mobile devices don't support auto-playing videos, an image will be shown instead of the video on mobile resolutions.
After that switch back to General tab and make your row fullwidth in Row stretch section.
Overlay option allows you to put an image or color overlay over existing background image/color/video. It is a great option to highlight text on the background. Open Row Settings, switch to Overlay tab and check Enable overlay checkbox. There will appear overlay options, where you can either upload an overlay image, for example a dotted image, or select a color with the colorpicker.
This effect enables you to add a background image that will move either to right or left, depending on the selected option. The best way is to use some repeating pattern as a background for flawless movement. To enable moving background, first of all, set an image in Row Settings>Design Options tab.
Secondly, switch to BG effects tab and enable moving background effect. You can choose movement direction from Moving bg direction dropdown list as well.
After that switch back to General tab and make your row fullwidth in Row stretch section.
Particles background is represented by infinitely flying particles all over the row background area. Particles background can be enabled both for background color and image. Simply add background color or image in Row Settings>Design Options and then switch to BG effects tab and check Enable particle background effect checkbox. 
After that switch back to General tab and make your row fullwidth in Row stretch section.