Manually installing new software and updates

Installing new software from a disc
Simply insert the CD or DVD in your computer's optical disc drive (if it has one; if it does not, see the note below). In most cases, a software installer will open automatically. If not, double-click the disc icon on your desktop and in the resulting window, look for a file with the word “installer” in the title. Double-click the file to open the installer and follow the onscreen instructions to install the software. You will need to enter an administrator name and password to install software.
Note: If your Mac does not have an optical drive to put a disc into, you can share the disc to your computer from a different computer via Remote Disc.

Installing or updating software from a downloaded file
Many software installers and updaters that you download from the Internet are disk image (.dmg) files.
After you download such a file from a website , an installer window will usually appear.
If you don't see an installer window, simply double-click the downloaded disk image file to mount the disk image on your desktop. Double-click the disk volume that appears and then double-click the installer or updater file to start the installation process.
If you see an application instead of an installer, go to "Installing software from a downloaded file that doesn't have an installer". Follow the onscreen instructions to install or update the software. You will need to enter an administrator name and password to install or update software.
Installing software from a downloaded file that doesn't have an installer
After downloading software, if an installer window doesn't open automatically or you don't see a file with the word “installer” (or similar) in its name when you manually mount the disk image, simply install the software by dragging and dropping the file or folder from the disk image to the Applications (or other) folder on your Mac. These types of files already have all the necessary files pre-installed and don't require a proper installer to install it—or an administrator name and password.

More information about installing or updating software
Many installers will ask you where you'd like to install your software. Updaters may ask you to select the application to be updated if it doesn't find it automatically. The Applications folder is generally the best place to install software. To avoid issues, do not rename applications. If you need additional assistance, look for a text or PDF file of instructions that may come with the installer or visit the developer's site.