The answer is - study! Take classes if you can and study at home on your own. You can post specific questions which you have problems with on here and we will try to help. Take time to read other posts on the forum to learn how it works.
Remember the rules of written English:
- Start every sentence with a capital letter.
- End every sentence with a single appropriate punctuation mark.
- Always capitalise the word "I" (first person singular).
Student or Learner