Modify an existing web app written in PHP and javascript

I need modifications done to an existing web application. The application is written in PHP with some javascript. There are two fields that need to be filled using an html editor. One field currently exists and is currently filled using a regular post entry the other field needs to be configured to open conditionally and then allow the user to enter information using the html editor. Both fields exist in the MySQL [login to view URL] is already an editor that is part of the project and is used in other areas. There should be limits to the total size and the graphics allowed in the fields. The existing editor, Rich Editor, seems to be configurable to enforce these limits. It may take a couple of hours to become familiar with the existing project.