This essay suffers from far too much telling instead of showing. Phrases such as "I have contributed to helping people," "Helping people is very important to me because I feel as if I am making a difference in someones life," "This contribution that I did is very important to me because it truly shows the type of person that I am," "I felt good about myself. I learned so much from helping at summer school and it made me realize that helping people is something that I like to do," and so on are flat, dull, and generally uninspired. You would have a much stronger essay if you eliminated these sorts of sentences (which is most of the essay, I'm afraid) and write a narrative essay explaining exactly what you did, specifically, to help, and describing your reaction to the experience to show us how it impacted you.
The good news is that you already have some good details in the essay that you can use as a starting point. For instance, this is good: "I remembered how my dad not knowing any English himself, struggled to help me every day. It took us about two hours just to do one worksheet." It is a specific detail that helps the reader to understand why you might find satisfaction in helping others learn English. Build on this. Describe (don't just say, show) how you overcame this difficulty, how you saw others struggling, what you did to help, etc.
Sean, EssayForum.com