Dear Worried Student,
First, I must applaud you for your desire to learn all about Hogwarts that you can, even the bits that previous teachers and students have preferred to gloss over (though an excellent read, I do not think that the currently available edition of Hogwarts, A History is entirely accurate in certain regards. However, as a basic guide to your understanding of the school, it is my most trusted source).
As to how to help the dear house elves, the best thing you can do is to promote their recognition, and the welfare of all house elves. Sponsor a cleaning of your House common room, perhaps, to show what dreadful lives these poor creatures live, or create a clothing collection so they can be outfitted properly. You can also become a member of the Society for the Promotion of Elfish Welfare (S.P.E.W.) by sending two Sickles to our Treasurer, Ronald Weasley. This will pay for your welcome pamphlet and badge.
Best of luck,
Head of the Office of Magical Law Enforcement