Add some getting started instructions to main README.md

Author: mfitzp

README.md

@@ -32,6 +32,20 @@ You can also find more PyQt articles, tutorials and projects
 1. [Currency converter](currency/) - "Doughnut" (PyQtGraph)
 1. [Solitaire](solitaire/) - "Ronery" (QGraphicsScene)
 
+## Getting started
+
+To use each app you first need to install the requirements. In most cases
+the only requirements are PyQt5, and occasionally requests. To install
+app-specific requirements change to the folder of the app and run:
+
+ pip3 install -r requirements.txt
+ 
+Once the requirements are installed, you can run the app using Python 3.
+
+ python3 <filename>.py
+ 
+The application window should appear.
+
 ## License
 
 All code is **licensed under an MIT license**. This allows you to re-use the code freely,