Others can share your story on social media if you make it easy for them. You could write a short summary along with the link and tell them why it's worth sharing. Also, encourage them by saying how much it would mean to you if they shared it. That often works!
You can share a link to your story and ask them to repost it. Simple as that!
Well, one way is to give them explicit permission and instructions on which platforms to share it and how. Maybe provide some hashtags or captions to make it more attractive for sharing. Another option is to have them tag you when they share it so you can keep track.