If you don't have an Apple ID, click Create Apple ID and create one--you will need to enter credit card information or a PayPal account.
Step 3: Look around
There are different sections of the Mac App Store to help you find the right app for your needs. The New and Noteworthy section features apps that have just entered the Mac App Store. The What's Hot, Top Paid, and Top Free section show which apps are popular at the moment. Apple also has a Staff Favorites section, as well as a Top Grossing section.
You can also peruse apps by category, either by clicking on the Categories button at the top of the Mac App Store, or by using the categories pop-up menu in the Quick Links section.
Of course, you can also use the Search field in the upper right corner to find an app based on its name, or to perform a search based on the type of app you are interested in.
Step 4: Buy an app
Found an app you want to buy--or, better yet, a free app you want to try? Great. When you're ready to buy, look for the price of the app in the upper left corner of the app's page. The price is actually a button. Click on it, and it changes to a button that reads Buy App. Click the button again to buy the app. If you haven't signed in, you'll have to do so at this point. If you don't have an account, you'll have to create one to complete the purchase.
After you've purchased the app, the Mac App Store downloads the app and installs it on your computer. (Your credit card or PayPal account will be charged for the purchase.) If you are running Lion, your Mac's screen will switch to Launchpad and you'll see the new app's icon at the end of the list as a dimmed icon with a progress bar labeled Downloading. You can do other things while you're waiting for the app to download; just click any blank space (or press the Escape key) to leave Launchpad. The new app will continue downloading in the background.
If you want to check the progress of your download, you can reopen Launchpad, or you can check the Purchases section in the Mac App Store app. In the latter, your new app will be at the top of the list, displaying a progress bar and the amount of time left on the download. Below that app are the other apps you have bought (if any).
The amount of time it takes to download a new app depends on the size of the app and the speed of your Internet connection. You can pause the download if needed by clicking the Pause button next to it in the Mac App Store's Purchases screen; to resume the download, just come back to the Purchases section and click the same button, which is now labeled Resume.
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