When you initially log into your account, depending upon the method in which you choose to log in, you will see various files and directories, among them, the one that holds the most importance is the / directory.
Do not delete or rename any of these directories or any files that you may find. These directories are automatically setup by the system and required in order for your hosting account to function properly. Deleting or renaming any of them will cause fatal errors that can only be repaired by deleting and resetting your account. Deleting and resetting your account will inadvertently cause you to experience DNS problems, these problems are not something that can be manually fixed, as they can only work themselves out in an unpredictable amount of time.
Of these directories, the most important to you is the / directory. This is the directory where you will upload your web pages and create other sub-directories that will pertain to your website and be viewable from your web browser.
Your site will not be viewable on a web browser unless the files are uploaded to the / directory.
The index.html page is the default entry page for your account and this file should be replaced by one of your own design.