select the particleShape1 in the ouliner. Then Go to the expression editor it's in window>>animation editors>>expression editor
Select particleshape1 and open the expression editor.Add the runtime expression
Then you should find a value called index (I'm not sure if adding it is part of the tutorial earlier on). then type in the expression editor the equation it says in the tutorial and select "runtime expression" as the type of expression. This simply means that it will be calculated as the render is run.
To add an attribute to the particle system select it in the outliner then go down to per particle attributes and add it on. YOu can then add that next expression in the same way as you added the first.
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