By default our servers will look for (in order) a file by the name of index.htm, index.html, index.cgi, index.php, default.htm, default.html or home.htm in a given directory and will load the first file it finds as the directory's (or site's) index or "home" page.
If you upload a file named index.html to your public_html directory this page will automatically be set as the index for the site and this page will be loaded automatically when entering http://yourdomain into a web browser.