You can comment two different ways in Slite - on the doc as a whole, or via highlighted text.
1. Comments for the doc as a whole
Just click on the 💬 icon in the top left of a doc to get started.
2. Comments on highlighted text
The "inline thread" style of comments are only accessible to teammates with Write permissions in the channel.
Highlight the text you wish to comment with your cursor and click the 💬+ icon in the toolbar.
You can create a line break by hitting shift+enter
You can add note links and mention people in your comment with @+name
When to resolve
You can resolve comments to get them out of the way. Just click on the "Resolve" button in the top right of an individual comment.
Viewing resolved threads on desktop
Head to the three dot menu in the top right of your doc to Show resolved comments, if you find you need them again later.
Use the three dot menu in the top right of a comment to delete the thread.
Who will be notified
All the people who have written in the document
Anyone @mentioned in the comment