To write a formula in organic compounds you first write about carbon and then hydrogen elements and then write the other elements in alphabetical order. And if the element or bond doesn’t have carbon in it. So, you can write all the elements including hydrogen in their alphabetical order. The small number at the bottom of the alphabet in the formula is the number of atoms of that chemical element in it. If you are struggling to understand the concept of formula, you can get help from a chemistry assignment solver and they will help you make your assignments quality better. Or you can read books, articles, and other things to uplift your knowledge.