How can I put a video behind this text?

I want to delete the laptop image on the website and have a rectangular section with a video in the background as shown here: !Screenshot - c3f2a5becac30771a4c025e38a5d9e06 - Gyazo and the text and buttons on top of it.

How would I go about this?

Here is my site Read-Only: [LINK]1
(how to share your site Read-Only link)