I have just started getting into using CSS and I was just wondering if this site here really contains all there is to learn about Cascading Style Sheets? http://www.w3schools.com/css/
So learn everything from there and then have a play with what I know right? Or, Are you saying to also look around other websites for guides and such?
Hell no. Reading the W3 specs or any sort of tutorial won't make you a "css master". You need months/years of experience of coding sites and getting them to look consistent in all types of browsers. Every time you code, you'll find a new bug and a new inconsistency between browser X and Y, and you'll have to find a solution, use a hack, etc.