If you've never used your ID to purchase anything from Apple - such as an iTunes track for example - you'll be prompted to review your account details and enter credit card information in case you want to purchase apps. You'll then be prompted to sign into your Apple account (or sign-up for one). To download the application, you'll need to click on the 'Free' or 'Payment' button in the top left hand corner. You only get one screenshot in some cases which is a bit limited but you can read lots of customer reviews, program details plus links to more apps by the same developer. The amount of information is a bit overwhelming at first with New and Noteworthy, Staff Favorites, What's Hot and the Top 10 Sales, Free and Grossing all vying for space in the main window.
The main window features a cycle of different promotions which can change several times while you're using the store. Once installed, you'll have access to the App Store via a blue App Store icon in your Dock or via your Menu Bar.
Download sizes vary, but it the system update can be as large as 1GB. To use the Mac App Store, you'll need to upgrade to OS X 10.6.6 via Software Update which is available here.
