Well it does but some newer games like Pokemon HeartGold, Black/White (2) have Anti-Piracy features that the blue card cannot circumvent unless you apply patches to your ROMs. That could be a bit hard/confusing for a newcomer in the scene. Your best bet to playing DS ROMs would be the Supercard DSTWO, because this card is able to circumvent every AP measure without needing to patch the games.
If you still want to try it out, just copy an NDS ROM (*.nds file) onto the microSD that you use for your blue card and start it, if it works you're all good, if it doesn't you need to patch it