It should be in yml format.
Add this template in _apps folder with file name as app name and open a PR.
Example: - typeracer-cli.md
---
title: // title of app
description: // description of app
logo: // At least one is necessary
- https://raw.githubusercontent.com/p-society/artwork/master/gifs/typeracer.gif
previews: // At least one is necessary.
- https://user-images.githubusercontent.com/24803604/39970250-e3d22eca-5705-11e8-9c89-472ff4d982ea.gif
authors: // can add more than one
- messi
- ronaldo
stars: 63 // number
repository: p-society/typeracer-cli // repository name
---
// Anything here in markdown format but its important not to add any images or video here.