It is a high time to group all the ideas that you came up with. Cross out any irrelevant ones and make your best to put them into a logical order. When ready with your ideas, organise them into separate paragraphs. Keep in mind the following layout of writing: an introduction, a main body and a conclusion.
Depending on the topic of your essay, you may need to do some background research. This could be to find evidence to support your point of view or argument or to find out what people who are experts in the field thing about a particular subject. Or it could be to find scientific or historical facts or statistical data.