The next stage is to make connections between your ideas, and to group them into sub-topics, expanding those that you can explore in more detail. Then see if you can put the groups into some kind of logical order, discarding those that do turn out to be irrelevant or bizarre. In most cases you will find that you have the beginning of an essay--something that implies a basic point of view you can explore further and refine into a fully developed argument.
There are several good books on using the brainstorming process to generate ideas for writing, including Tony Buzan's Use Both Sides of Your Brain and Gabrielle Lusser Rico's Writing the Natural Way. If you are still unsure about the topic, you should consult your instructor after you have done some thinking about the topic on your own.