Adding a background image behind a video on a custom liquid section

Store Design
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1

Can someone help me? I need some help on adding a background image behind a video on a custom liquid section.

2

@DonVeto - you can use background-image css property to set image for this section

3

I will contact you by email.

4

Hey, can you fix a code for my website?

I need it behind the signup box, here is the page: asmotromso.com