If you want to develop a mobile app, start with gathering all the needs and requirements that you have for your ecommerce business. Once you are done with your requirement document that is BRD(Business Requirement Document), you can now hunt for an ecommerce development company that can help you with your ecommerce software solution. Once your search is over, you can discuss your BRD, features and functionalities, Design, price, time factor etc. in detail with them and they will then start working on your custom ecommerce solution taking all your needs and requirements into consideration.