Just about everything on the Mac is pretty easy, with the exception of copying CDs or DVDs, without a 3rd party program such as Toast. Since most Macs only has one CD or DVD drive, you must first create an image (copy) of the CD or DVD to you hard drive, and then you take that image, and you can burn it to your blank media.

Here is how to do it:

Open 'Disk Utility' Finder -> Go -> Utilities -> Disk Utility

Next, insert the disc that you would like to duplicate. It cannot be an audio CD or a copy protected DVD. On the left side of Disk Utility, select on the name of the CD/DVD you inserted.

Next, from the menu, choose 'File -> NEW -> Disk Image From (the name of your disc)'.

Type in a name for your disc image, select the location (I use the desktop).

Choose the 'Image Format' -> 'read-only' (this will speed things up), and then click on 'Save'

Now the Disk Utility will start to create an image of the CD/DVD and save it to the location you specified above.

After it is complete, Eject the disc from the CD/DVD drive. Now, look back at Disk Utility, and you should see your newly created image. It will have an extension '.dmg' Select it by 'Clicking' on it, and then click on 'Burn'

Disk Utility will ask you to insert a blank CD or DVD. Setup any options you may like to have, and click on 'Burn'

Now, you will see a progress indicator. When it is complete, you now have a copy of the original disc.

If you want to create more, simply insert another blank disc, and click 'Burn'. When you are all done, simply drag the disk image file you created to the trash and empty it. If you don't.... you might start missing some hard drive space, since the image files are very big.