You dont.... You extract the .nds file with Winrar.... Google it, download it, use it.... Edit: Here.... http://download.cnet.com/3001-2250_4-10007677.html?spi=b4c0892b6823cf4b11bcf717d81c3458 After you install it then right click on the .rar that you downloaded from RomU and click on "Extract Here." Wate a bit and the .nds file should come out.