Content permissions
If you have the correct permissions set, to the left of the file name you will see a check box and to the right of the file name you will see View, Edit and Delete.
If you do not have the correct permissions set you will see a lock symbol to the left of the file name, and to the right of the file name you will only see "View".
If you have full admin permissions, you can give yourself permision to edit the page. If you do not have full admin permissions, ask your site admin to give you access.
See How do I give/remove permission to access content/features?
