- Open a forum discussion thread
- Select "my annotations" from the pull-down menu at the top right
- Highlight text in a forum post then press the keyboard "enter" button (or mouse over to the right until you see a vertical yellow line and click)
- A small dash will appear in the margin
- Type your annotation
- By default your annotations are public. You can make them private by clicking on the small o icon to the right of your text.
You can view your annotations or all public annotations by clicking the summary link beside the annotations pull-down menu.
More information:
Help file
Marginalia web