How do I fix the screen?

iFixit doesn't have any guides for your laptop, but fortunately they do have a copy of the Lenovo Hardware Maintenance manual. It has all the information you need to remove your LCD and replace it. The section of interest starts on page 57.

Lenovo 100e 300e 500e Chromebook Gen 3 Hardware Maintenance Manual - iFixit

As you work, take lots of pictures every step of the way. Then once you're finished, you can use those photos to create your own iFixit guide to that repair. It's easy, fun and will earn the appreciation of the repair community for those who come after you with the same problem.

Adding images to an existing question - iFixit Repair Guide