Create or Copy & Paste HTML. Just put the HTML code into form. If you want to create a landing page you can use the templates
from this site. Be sure you are replaced all resources and information to your.
Tip: want to find niche for your app? Try making app for your social group/language. If you know several languages, use less popular one. Targeting small groups of people can make your app a lot more popular. You'll be able to find niches that are free from huge players on app market and make a great app for your social group.