Ive downloaded and been working with Umbraco 4 via a Microsoft Web Matrix platform.

I have no idea if it is beyond Umbraco 4 I am using ie version 4.1, 4.2 etc. But when I play around with the UI of Umbraco and it locks me out it says im using Umbraco 4.

Could someone advise me how to find out what version of Umbraco im definately using and more importantly, is this book aimed at teaching those using Umbraco version 4?

Thanks