Understanding histogram

Thank you for the class, Helen, but I have a question:
When I see on a histogram of an image that it hits the left side ( that black pixels are lost) - does it make any sense to try to correct it? I tried to change blue and green colors via color channels, but I think that it only made things worse.
This is a screenshot of the original image:
And this is after :
Thank you for your class.
Regards,
Dina