What do you mean by adding an After Effects project to a website? You can put videos on a website, but how well it runs will depend on your streaming service and the render settings you use. The easiest thing to do would be to put your video on YouTube and embed it on your site.
You shouldn't just start grabbing templates and trying to use them without a basic knowledge of how to work with AE or you will end up frustrated. Start here to learn After Effects.