These instructions will take you through the steps of downloading and starting DS9.
From the DS9 Website, click on the link for the version of MaxOSX you have. You will need to have X11 installed in order to use the X11 version.
The download will automatically begin when you click the link. The file will download to where the browser preferences are set to (normally either the desktop or the Downloads folder in your home directory).
Aqua install:
After downloading, the disk image is automatically mounted and a new window opens containing the SAOImage DS9 program. To install, drag the program into your Applications folder.

X11 install:
Double-click the .tar file to unzip. The program will appear as "ds9" in the same place as the .tar file.
Drag the program into your applications folder to install (you can use the same screenshot as above, but the X11 version looks like a gray box instead).
To create a shortcut on the taskbar, drag the icon onto the taskbar.

To create a shortcut on the desktop, ctrl-click (or right click) and select Make Alias. The alias will appear in the same folder as DS9, simply drag the DS9 alias to the desktop.

The first time you open the program you will get a box asking if you want to open the program, click Open.

by Rachel Ross