The first thing that you should do is do some research on the internet to see if anyone else had invented it. If not you should search through the US Patent information to see if a patent was ever created for your type of invention. If there is no patent, go to the next step.
The easiest thing to do is to work with a company that can help you to make your dreams a reality. A company that can help you to present your ideas and get your product to the right companies. One company that is very reputable is Lambert and Lambert in Minnesota. They offer free advice and if they think your product is marketable, they will help you to get it to the right company.
Call the company and make an appointment. You will want to bring in a model of your invention and/or a complete description of your ideas if you don't have a prototype. Write down exactly what your invention entails in as much detail as possible. Then when you meet with them, you can present it and they will tell you how marketable it is. If they decide to help you, they will work to present it to different companies and help you to go to the next step.
Once your invention has been approved and sold to a large company, get ready to reap the benefits of becoming the next great inventor. It may take a year or two, but the benefits are worth the wait.