You may be able to take some acceptable photos of the birds at your feeder with your current camera. An extender tube will increase the magnification of your lens. Professional nature photographers always try to get the bird's eye in focus. You can take better photos if you know your subject. Answering these questions allows you to anticipate the bird's actions and set up your camera and tripod for the best shot.
Professionals use slide film.
The rest of us use print film. It is more forgiving and easy to develop and to view. Slower films will produce higher quality photos. As you experiment, you will find that fill-flash will greatly improve your photos. Getting closer to the bird will help too.