First of all, you need hosting and domain name for your future website. Some providers offer quick installation of various CMS including WordPress. If your hosting does not provide this service then please read about the installation of CMS WordPress through FTP in a standard way below.
Installation through FTP
WordPress is available for download at https://wordpress.org/. Download archive with WordPress. The archive should be unpacked at your computer. Then unpacked files should be uploaded to your hosting. To do this you need an access to FTP-server (offered by the provider after hosting purchase) and FTP-client for upload of files directly to the server, for example, FileZilla. FTP-client is a special program for easier access to FTP-server. Copy unpacked WordPress files in a root directory of the web server with the help of FTP-client (as a rule, these are directories called PUBLIC_HTML or WWW). Once files are uploaded just open your website in the browser (by entering URL of your website) and follow instructions on the screen. You may also need to know access details to the database (MySQL) provided after hosting purchase.