I've put it in the memory card for my R4... but when I open my DS...

I downloaded a few games on romulation... I put them in the memory card for my R4 like what I used to do.. but this time.. when I opened my DS, the games weren't there! o.o help?

You probably have not extracted the files. When you download games from Romulation, they will be in RAR format.Check out this tutorial.
https://www.romulation.org/forum/index.php?topic=3880.0

Did you do every thing right?
Take the R4i card out and back in that sometimes solves the problem too..

first, make sure you have the Firmware on the card (v1.18 recommended), and make sure that the games are extracted from the rar file by using winRar or 7-zip.