Follow the steps to open a file from section Opening Files.
The file appears in the Translation window. The first translatable segment appears in a blue background and your cursor is in the target segment by default.
Place the cursor in the segment where you want to add a note.
Click the Review tab.
Use one of the following methods to open the Notes dialog box:
Click Add in the Notes section
Right-click the segment, and click Add or press Ctrl+Shift+N
Click Add in the Editor
The Add/Edit Notes dialog appears.
Select the Type of Note.
Enter the note.
Click OK.
The note appears in the Notes tab. The Notes icon appears in the Status column as shown in the example below.