div inside div

hello
I would like to know how to put a div inide another div.
i try switch my theme’s slideshow for an animated banner. So after i delete the slide show to the specific page, i use your plugin to add a new banner, but i cant put between menu and page content.

this is website and the background image is the image i want animate.
http://icsaude2016.utad.pt

thanks

https://ww.wp.xz.cn/plugins/header-footer/