First, you hire someone to implement your "idea" in the form of a specification for an "invention". Ideas are not patentable. Inventive designs might be patentable if there are new and non-obvious, assuming you file a proper application and attend to the inevitable rejections and objections. A typical budget for a single-country patent is about $10,000, unless the invention is very simple or very complicated.
contact a patent attorney or find one on the internet and look at their website as their website probably will provide you all the information you need and are inquiring about. Some have Q&A type information.
www.ustpo.gov
