Need help adding my Lightroom from external hard drive to new Mac desktop

I use Lightroom CC on my apple laptop now and I would like to use it on my new Mac Desktop too.  My laptop not doing great its getting old so I had my computer guys backup everthing to a hard drive. I then downloaded the Lightroom app on my Desktop and plugged in my hard drive.  It cant find anything nothing looks the same and Im not very good at computers.  I cant figure out how to find my presets or folders. I have bought books looked through tons of forums and utube.  please help