Responsiveness of a page

I am having loads of trouble with making my web pages responsive, I am only able to make the images and text responsive in most of the stuff I do.

I’ve tried to do stuff with Media Queries, but I don’t really get how to do stuff with media queries, I am struggling to make my video, navigation bar responsive.

The only thing I don’t have trouble with is resizing, but other than that I am almost good for nothing.