In order for the nameservers to be updated, it can take up to 48 hours after entering them through your registrar.

During that time span, you can connect to your FTP service and upload your website files on your server, by using ftp.top.host (replace top.host with your own domain name), the primary nameserver’s IP address or the temporary hostname with the access information (username/ password) that you can find in your web hosting activation email.

For instance, if you’re using FileZilla, don’t put ftp.top.host in the field Host (replace top.host with your own domain name). Instead, enter Top.Host’s IP address and the access information (username / password) for the FTP service.