Paste the Webhook URL in the Slack Account Hook field.
Add your Slack Channels to post to:
If you would like to be notified for every comment on a graph, tick the check box Transfer all user comments by each channel. If this box is left unchecked, you must use the @slack-<ACCOUNT_NAME>-<CHANNEL_NAME> syntax in order for comments to be posted to Slack. You may use @slack-<CHANNEL_NAME> if you are only using one account or referring to the first account.