If a document has been disapproved can I edit it and send it back through the system for approval?

The original disapproved document cannot be edited. However, it can be copied. Open the document through Document Search or from your Action List and click "Copy." This will generate a document that is identical to the disapproved document except that it will have a new document number assigned and will reference the original document number from which is was copied. Then you can make your changes on this copy and re-submit it for approval.