The following is a template for an application wiki page. These should be created as subpages of wiki.gnome.org/Apps/. To create the header, generate a png with Inkscape replacing your app icon and app name in the header svg template. There is also a full home page svg template in case you want all measurements. When deploying, repeat the splash png and the navigation bar on any page listed in the navigation bar and change the bold style of the navigation bar to its current page.
Finding a task
To find something to do, simply pick a bug from this list of newcomer bugs.
To build the app you can follow the newcomers guide on building GNOME Apps.