Storing CSS Files

[ski diva]

I'm just getting started with vbulletin, and in the control panel under styles and templates, there's t his:

Store CSS Stylesheets as Files? - If you would like to store the CSS stylesheet for each style as a file, you must ensure that you have a directory called 'vbulletin_css' inside the 'clientscript' folder, and that the web server has permission to write and delete files within that directory

My question is t his: where is 'clientscript,' and how do I find out if my web server hs permission to write & delete files within that directory?

Thanks!