How to add slack notification everytime there is push or other activities on selected git repository

1. Get slack incoming webhook url for a particular channel here
   https://yourslackorganization.slack.com/apps/A0F7XDUAZ-incoming-webhooks (or try search on google to get the page).
2. Open any gitlab project. Choose settings > integrations. Choose slack notification. Paste the webhook URL and set username (name to send notification in channel)
3. Click the test button to see if the integration works.
4. That’s it