Here is how to add slack in trello
- First click on the "Boards" link in the left sidebar
- Then click a board in the workspace section
- In the board view, click on the "More" menu (three dots) in the top-right corner
- Scroll down in the menu settings
- Then click on "Power-Ups" option in the menu
- Click on the "Automation" category in the left sidebar of Power-Ups window
- Scroll down in the automation menu
- Finally click on "Add" button under the Slack integration in the Power-Ups list



