Installation is very simple: install the app on Chromecast tablet / smartphone, plug socket on Hdmi TV, grab your WEP key (wireless key to your box). Launch the app from your tablet. Your Chromecast (connected to the TV) and your tablet will recognize, insert your key to authorize wifi internet access Chromecast and go!
You just then throwing Chromecast compatible app from your tablet and then the "caster" on your TV. Eg Youtube.