To help you get started we have provided a template of the required ui.r and server.r and supplementary code.r files to run a mini-app and generate a plot.
When you select 'New Mini-app' a pop-up window will appear. Enter the name of your mini-app and choose a template from the dropdown menu. 
Click on 'Create mini-app'. This will open ui.r, server.r and code.r templates which can then be edited to suit your purposes. Note that the code.r file is only used to add additional functions to the app, is not mandatory and can be left blank.