People have different style for making a website, u can make it the way u want. All pages are linked together in some way. Usually people follow a common style so that their fellow patners or the next person handling it can understand the flow and that is as follows:-
1. Home page is named as index.php (.php extension is a page made in php, u can use any language or say file extension u want)
2. if u have a commom header and footer for all pages then header.php and footer.php respectively.
3. Pages are named after their purpose, for eg. Contact page -> contact-us.php , About Us page -> about-us.php , Terms of service -> tos.php , etc.
Again u can name the files the way u want. But the above way helps everyone to understand and easily remember wer ur files are.