Canon Community

I would like to purchase a used 100-400 mm Canon lens for my Rebel SL1 and my research appears  to show more than one different 100-400 lens, not surprising given the age of my camera. Which one should I be looking for and any specific tips would be ...

I am very new to this. I recently purchased a Rebel SL1 with lenses, etc. A lightly used package and have taken some pictures and would like to load them into my MacBook Air (or maybe to my iPhone?) But now I am very confused. If someone could shed s...