Open a Finder window and select a folder from the Sidebar e.g. Applications. At the bottom of the window it should tell you how many items are in the folder and the total amount of free disc space available to you.
If you want to free up space there is a few steps you need to go though,1. push start button2. CLick the button on the menu that says "Control Panel"3. click the big button that says perfomance and...
You have to go in and delete or compress your existing files.One of the best things to do first is to run "Disk Cleanup" under All Programs > Accessories > System tools of the "Start" menu....