In order to set up an alert make sure you have the indicator you want to set an alert to on your chart, then click on the alerts icon represented by an alarm symbol under "watchlist".
This will open the alert creation menu, in condition select the indicator you want to add an alert to.
Then an alert condition dropdown menu will appear below, by clicking on it you will see all the alerts conditions available.
The options section tells you when the alert will trigger, you will generally want to select "once per bar close".
Once done click on Create. For more information on how to set up TradingView alerts go here.
When you create an alert using certain indicators such as The BirbicatorPRO you might see a warning message, this is caused by internal Pinescript functions used in the script that may have a repainting behavior when set in a specific way.
The alerts provided by BirbicatorPRO do not repaint and as such, you can click on continue anyway.