Since you didn't post any of your angular code I'm going to make some assumptions (ex: using basic auth + get call).
For $http.get there is a headers property that you should be able to use.
$http.get('< your url here >' {
headers: {'Authorization': 'Basic < your auth string here >'}
});
If that doesn't meet your needs I encourage you to use google to find something. Authentication and requests done via angular is well documented.
Auth example
Google - Angular auth header