Trying to install business portfolio but nothing happens to my homepage.

So im trying to activate a new theme, actually my first one to my homepage. But nothing really happens. Im using filezilla and transfering first the whole business-portfolio and then the busniess-portfolio-child. (the first thing i tried was only uploading the business theme, but none of these work.

Have read stuff about some admin panel? Too me this seems to be installed into the panel already? The WPMU DEV videos dashbord doesnt really match mine. Or is the admin panel an Plug in that i need to install? And i have all the latest updates.

Thanks!