Mainly we have three ways to install a WP Theme
1) via the dashboard, we can select from a list or choose by name or other ways
2) via the dashboard, we upload a zipped theme fie
3) we FTP the theme folder, via FileZilla or another FTP program, to the /wp-content/themes/
Before the installation take a backup.
In case of white screen remove the theme folder from the /wp-content/themes/
