Neither "essay" nor "idea" need to be capitalised and "How does I can ...?" is incorrect. I am sure you know that. In your last sentence, you said "expending" again. You must learn to take care with your posts. You have been using the forum long enough to know that we do not do your work for you. Write a short essay, post it in the Editing and Writing Topics section and we will look at it. Why have you chosen an essay topic that you don't understand how to expand upon and can't write an essay about? Your method of learning English seems to be somewhat haphazard to say the least.