When upload template dont know how to set up it for full screen

[Batman1]

Hello , as decribed i have no idea how to cover whole site by my template , that border green shoud be covered by template with Joker suppose its easy but cant find solution anybody for hep ?

 

[Jord Kuijer]

Hi, when you click on the

middle button here "edit section"
When you did that you need to

expand the section so it covers the whole screen. You can alse uncheck the container.