How to Take a Screenshot Of a specific area on your computer
How to take a screenshot of a single window in Mac OS X
How to take a screenshot with your iPhone or IPad
HOW TO KEEP YOUR MAC SAFE FROM MALWARE
Because of the way Apple built their Operating System, Malware or Malicious software is something Mac users don't come across often. Occasionally, Mac users may fall prey to a bad installer or click on something that they shouldn't to install a software update or plug-in.
While there are a number of things that can be done to configure your computer to protect it against malware, the first thing that you can do yourself is to make sure that when you need an update for something such as Flash, you should ALWAYS go directly to the Software Developers Website. In this case, https://www.adobe.com/downloads.html
BACK-UP YOUR MAC
Backing up your computer is important to ensure you don't lose data to hardware malfunction, human error, or software corruption. Apple has made it ectremely easy to back-up your computer. So why not do it?
It's simple, plug in an external hard drive that’s at least the same size as your internal drive, and then go to your Apple Menu. Scroll down to System Preferences > Time Machine. Flip the switch from OFF to ON, and then click “Select Disk.” Select the external drive you plugged in and go ahead and check the box labeled “Show Time Machine status in menu bar.” Time Machine will start making back-ups of your Mac. It is really that easy.
Orange County's Premier On-Site Macintosh Specialists