I will be able to take one step towards my goal.
Since this is your only opportunity to impress the reviewers with the importance of your goal, be definitive in presenting it. Right off the bat, tell them what the goal is, why it is important, and how it will affect your future. Summarize the detailed explanation to follow because the reviewer will use the summary to assess if your letter is worth reading to the end or not.
My passion.
Good show for the development of your interest. There is a good reference to the extra curricular advancement of your interest by joining the school club. The problem is, you have not done enough to show that you are actually passionate about learning about coding. Beyond the regular classes in school and the club membership, there are no notable achievements, awards, or participation in the coding world to highlight the degree of your passion and possible success as a future programmer. You only present a very basic interest in it actually, based on what I have read in the paragraphs so far.
There is no clear connection in your statements regarding the relevance of your hobby, the mental wellbeing of your FB page members, and coding / informatics. Add more information to the point where the connection can be made back to Computer science.