What is the best aerobic exercise i can do to take care of my spine?

Whatever you find. Most comfortable and enjoyable with cross training recommended to avoid overuse injuries. Swimming, biking, walking, jogging along with the use of various gym equipment except possibly a rowing machine. In addition, stretching routinely and core strengthening exercises should be part of your routine.
Low impact. In general I recommend low impact activities such as bicycling or an exercise bike, an elliptical machine, or stairmaster. Swimming is also great. Remember to also do a lot of stretching to keep your spine loose, yoga and Pilates are great for this.