Adding schema.org to site

I want to add schema.org to my site, I've read some guides for that and I understood the way I should do that. But should I add these tags for example for images and url:

<figure itemprop="associatedMedia" itemscope itemtype="http://schema.org/ImageObject"><a itemprop="contentUrl"  href="someurl" rel="bookmark"><img  src="someurl"/></a></figure>

to all my images, all my urls, all my pages or there is a way to do that globally for my site?