You seem to be in an, "I know I want to do something but not sure what it is yet" phase. The enthusiasm is great but without focus it can lead to business demise. For now, pick one idea to for start. Test the waters by starting small and continuously seek customer feedback on your idea / product. Then revise, revise, revise until you have a viable product. The book that describes this approach in detail called, "Nail it, Scale It". Another similar book is called, "The Lean StartUp." The material may be a little dry to an 18 year old but the advise is sound. I'd suggest you start by reading the Amazon reviews on these and other business approach books to get a flavor of what resonates with you... Then pick a solid methodology to approach your business with.