1. Goto Manager >Settings > Slack . 
  2. Click on Webhook endpoint. You can also generate it by clicking on this https://api.slack.com/messaging/webhooks 
  3. Scrolling down will lead you to the Channel Notifications where you will find the options of  Leaves, Expense Claim, Job application, News, Assets, and Appreciations for which you will be notified in the slack.
  4. Scrolling down will lead you to the Employee Notifications where you will find the options of Salary Slip, Asset Lent, News Published, Appreciation Received, Leaves, and Expense Claim for which you can notify your Employee on slack.
  5.  Click on Update to proceed.