When you open a document, look for and click the Add Note button. If there is no button, you will not be able to add notes. In most cases, the status of the document determines whether notes can be added or not. Once a document is approved, it is considered locked and may not be altered. Also, you will not be allowed to add notes to documents that are derived from other documents. For example, the Current Set is derived from the Construction Documents, so you will not be able to add notes. Once a note is added, it will follow the document from then on.