How do I create a random coloured flashing background

[m4mm4l]

How do I create a background that has random coloured flashing lines?

[Dreadnought]

I suggest you read the Turing Walkthrough (http://compsci.ca/v3/viewtopic.php?t=8808), especially the section on basic graphics.

You should also have a look at the turing documentation of the Draw module that contains all the basic commands to draw graphics in the run window as well as the Rand module if you don't know how to generate random values.