Hello,
Thank you for contacting us about editing your site. Here is a link to our FTP Getting Started guide. It includes in-depth information on what FTP is, and how to use it FTP.
We also have a helpful guide on how to edit files on your server.
If your site was built using a CMS such as WordPress, Joomla, Drupal, etc, you should instead login to the Admin dashboard and modify your site from there.
Let us know if you have any further questions.
Thank you,
John-Paul