First, welcome!
Second, I'm not a mac user, but I would assume this type of thing works similarly either way.
Plug your dx into your computer via the usb cable that came with it (the one that doubles as the charger cord).
When you do this, you should get a notification in the bar saying something like "usb connected".
Click that notification. You should see a popup with a few different options. The easiest to do what you want will be to click usb mass storage. Then, using a file explorer program (again, I'm not too familiar with macs), locate the phone. Within the list of folders from your sd card, you should see one called DCIM. This is where your pictures are stored by default. Simply select all the ones you'd like to copy to the computer and paste them into the proper folder on your mac.
Hope that helps! Feel free to ask any questions.
Emitted from X.