how to see a theme on Magento 2?

Hello there,
Do you know how to see a theme on Magento2?

I bought yesterday this theme from your page and now I want to add it to my online store. I added on the files administrator of CPanel inside my Hosting. Also, I can see the option inside my Admin Manager of Magento and I select it but when I want to see it on my site: only appears the LUMA theme instead of Precia theme that I have added.

Could you please show me how to add it in a correct way?

Thanks in advance!

There should be information how to install the theme on the theme documentation. You can refer it to get some help.