What should a " letter of interest that presents a personal statement of his or her academic goals and intended major"
include? How do I write it? 
Thank you! (It’s for an undergrad scholarship)
I plan to attend XXXXX University in Fall 2015. While at XXXXX, I plan to major in Y. Major Y will prepare me for my desired career in Z. I became interested in major Y / career Z since A, when B experience happened. To complement my classroom experiences at XXXXX, I plan to join A, B, and C extracurricular activities. Additionally, I hope to (do research under D professor so I can learn more about E subspecialty / get an internship with F company / volunteer with G major-related non-profit) so I am prepared for (work force / grad school). Receipt of J scholarship will significantly reduce the financial burden of attending college, and will help me achieve my aforementioned goals. I appreciate your consideration.
Something along those lines will work nicely. Obviously you will have to bulk it up, modify where necessary based on your own goals, change the order to make things flow, but that should be enough to get you started. That’s the same general format I used for many of my scholarship essays, and I won a great deal of them.
Thank you @bailey57 
Just as an FYI, bailey’s post is spot on. He covered the gist of how to write a personal statement nicely. You can also learn a few pointers from professional schools personal statements such as guides on how to write a nice medical school personal statement such as this one: http://ourhealthcrisis.com/
Hope that helps and keep us updated.
Thank you! And I will do (keep you updated )!