To print on discs, you have to install the Epson EasyPrint software:http://support.epson.com/easyprint/
It sets up necessary settings automatically. If this doesn't help, follow these steps:
1. Select your printer (CD Tray) in the paper template dialog. To do this, open the Design Element tab of the Inspector (Cmd-1) and click on the Change Layout button. Select "Epson Tray Type 2" from the list.
2. Open the Page Setup dialog (File > Page Setup). Select A4 (CD/DVD) or A4 (manual feed) paper format.
3. Open the Print dialog (File > Print).
4. If necessary, set up the resolution, bleeds, etc. Do not change the tray type here. Click the Next button.
5. In the system print dialog, make sure the correct printer is selected.
Click on the Layout drop-down list and select the Print Settings section. Set "Media Type" to CD/DVD.
6. Click Print.