If you have the Content Contributor security role, you can create and edit your own content. To edit or replace content published by someone else, you’ll need the Content Managers security role.
The content security roles are:
Content Managers – Can publish, edit and delete all content.
Content Reviewers – Can approve other users’ content, and publish and edit their own.
Content Contributors – Can create and edit their own content.
Content Viewers – Can view content only.