Mobile app development is a term used to denote the act or process by which a mobile app is developed for mobile devices.
Web development is a broad term for the work involved in developing a web site for the Internet (World Wide Web) or an intranet(a private network).
You need to promote your business along with a good web design. All you need is to opt for search engine optimization or SEO for this.
Search engine marketing (SEM) is a form of Internet marketing that involves the promotion of websites by increasing their visibility in search engine results pages (SERPs) primarily through paid advertising.