I need some advice and corrections. please help!
I am not involved in every club in my school; however, I have great passion in soccer team I participate in. Being the captain for my school's soccer team for two years, I have had the opportunity to challenge myself. The team members included students from 7th Grade to 12th Grade. This wide gap in ages made it difficult to unify everyone as one whole team; however, in my role as captain, I had to encourage everyone to have the same goal. Every time when the team went out for competitions, I had the most important responsibility. I had to encourage my team and make sure that everyone was concentrating on the game. Because I didn't want to lose, I would sometimes yell at the members for the mistakes they make, but also compliment them for the nice plays they create. The team was becoming stronger and indomitable as I trusted everyone in the team.
"I am not involved in every club in my school; however, I have great passion in soccer team I participate in."
I agree with Yang; the adcom already knows that you're not involved in every club. Also, I think "great passion in soccer team" should be "a great passion for the soccer team"- sometimes, articles are rather necessary. Or, if you want another option, you could say "I am very passionate about the soccer team I participate in."
"Being the captain for my school's soccer team for two years, I have had the opportunity to challenge myself."
Change "Being the captain" to "As the captain."
"Every time when the team went out for competitions, I had the most important responsibility. I had to encourage my team and make sure that everyone was concentrating on the game."
These two sentences are the perfect opportunity to demonstrate the versatility of your syntax and use a colon: "[...] I had the most important responsibility: I had to encourage my team [...]". Additionally, you can start the sentence as "Every time the team went out" or "When the team went out", but it's redundant to use "Every time" and "when" at the beginning of the same sentence.
"Because I didn't want to lose, I would sometimes yell at the members for the mistakes they make, but also compliment them for the nice plays they create. The team was becoming stronger and indomitable as I trusted everyone in the team."
Again, I agree with Yang. Not wanting to lose and sometimes yelling at your teammates could possibly be construed as a bad thing. Also, your last sentence could be restated to provide a stronger finish for your paragraph. First of all, "was becoming" should be "became"; secondly, you never mention how this trust develops. Did you not trust them in the beginning? Why not?
Your response is perfectly adequate for the prompt, but it doesn't give me much of a sense of who you are as a person. Perhaps it would be more effective to give a specific example of a time when you demonstrated your leadership as team captain, maybe by encouraging the younger members and helping the improve their skills, or a time when you demonstrated good sportsmanship despite adversity. In any case, I feel like your essay is rather heavy on platitudes and light on personality.
I am not involved in every club in my school; however, I have great passion for soccer soccer team I participate in. Being the captain for my school's soccer team for two years, I have had the opportunity...
I see Yang and Rebecca gave great feedback here! I think this essay needs one solid, meaningful observation right at the end. Make it the "moral of the story." Give one more excellent, thoughtful sentence.