I am a bit op a PHP purist and have created most of the components of bootstrap in pure PHP.

Open a view file and click the Bootstrap button

A window opens up where you can pick a component. Click on Alert.

Click on any of the colors

There is a dialgo for bootstrap attributes also

Click save to insert the php in your view

Save your page (ctrl-s) and Run [F9] the view or Use the debugger [F8]

You should see this.

Or this if you opent the page in the browser [F9]