If you're hoping to play DScraft on your Nintendo DS Lite, you'll need to look elsewhere. The homebrew Minecraft clone was built exclusively for the original Nintendo DS and simply isn't compatible with the DS Lite. Here's why.
If you want a block-building experience on the DS Lite, check out Pocket Mine 3D, available via the DSi Shop (on DSi/3DS) or the Nintendo 3DS eShop. It offers a similar creative sandbox tailored for the platform.
Bottom line: keep your original DS if you're set on DScraft, or explore the alternatives above for your DS Lite.