Installing a WordPress theme is easy. But keep in mind that if you’re switching from an existing theme, then you may want to keep backup of database file before changing WordPress themes. If it’s a fresh WordPress install then proceed as follows
First thing you need to do is login to your WordPress admin area. Next, click on Appearance » Themes.
Once you are on the themes page, click on the Add New button at the top.
From there you’ll see an option for “Upload” at the top of the screen. Click the “Browse” button, navigate your computer files and select the .ZIP file of our theme that you downloaded earlier. Select the file and click Install Now.
WordPress will now install your theme and show you a success message along with the link to activate or live preview.
Click on the activate button, and you’ve successfully installed and activated your WordPress theme.
Note: Depending on the theme, it may add additional settings options that you may need to configure either through the theme customizer or through a separate options panel.