Your page url is how people find your page. For example, the url https://linkna.me/tochiuzo is your page url.
To change this, simply visit your page and click the "Settings" link.
These are your page settings. You should see "Page Url".
Enter your desired page url and hit enter and it will save and thats it!
Please note, if the url that you want is not available, it will let you know and you will need to try another url.