You use the http Service to make http requests
There's more info here: https://angular.io/docs/ts/latest/guide/server-communication.html
I didn't read Google's full documentation but the function below should get you started.
addNewUserToGroup(email: string, role:string, groupKey: string): Observable<Hero> {
let headers = new Headers({ 'Content-Type': 'application/json' });
let options = new RequestOptions({ headers: headers });
let data = {
email: email,
role: role
}
return this.http.post("https://www.googleapis.com/admin/directory/v1/groups/"+ groupKey +"/members", { data }, options)
.map(response => response.json());
}
Good luck