Safari can't open the page ... because Safari can't find the server

I just downloaded WordPress through a Hosting Service and got an email from WordPress that my site was active and I could access the admin page from https://sitename.com/wp-login.php, but when I try to open the link Safari gives me the message:

Safari can’t open the page … because Safari can’t find the server …

This is my first time doing anything with WordPress, if someone can help me please do!