Prime meaning first, meaning original – and the basis, of course, of the word, "Primer".
And that's what this is. It won't tell you a great deal (other than anectodal) about the history of Chaos magic, but it will tell you about doing chaos magic.
The Contents rather spell it out:
Chaos is everywhere
Liber Nice and Liber Nasty (Discordianism and the Cthuhlu mythos and magic).
This work is aimed at practitioners, rather than anyone else, but practitioner or not, reading it will give you a general overview of what Chaos practice is about – as much as anything can, that is.
For a study of chaos magic, this may not be the best book (though it should not be neglected).