"URL" is another way of saying "web address." It's the words, periods and slashes in the address bar of your browser. It's the address of the webpage you are on.
Look at the URL in the address bar of your web browser. Note the word before the first period.
In this image, the word before the first period is "ski." Yours will probably be different. Make a note of this word. It is your domain name.
If your url looks like this, then your word is "sports."
If the docs say,
"You can navigate directly to the Roster section by typing <fill-in-your-domain-here!!!>.ampsport.com/roster"and your domain name is "sports", then you would type
"sports.ampsport.com/roster"into the address bar of your browser, if you wanted to navigate directly to the Roster section.