Wow. ok. Easiest way to do it is to go to your admin panel (a.k.a. Dashboard) and click on Themes under Appearence; then you simply search for Virtue, install and activate.
Other way is to use an FTP client. You would go to https://ww.wp.xz.cn/themes/virtue/ and download the theme to your computer, connect to your site with your FTP client and then move the theme folder into wp-content/themes/.
There isn’t a specific way to install this particular theme, it’s the same any WordPress theme is installed, you could’ve just used Google and you’d get a thousand results.