do i need a r4 cardtoput ds games on? thanx.

if im putting downloaded games on a ds memory cardso i need an sd card or a r4 card..??

You need a flashcard. R4 is one example but I would prefer CycloDS Evolution (for ds/dslite).A flashcard is sized like a normal nds-game and has a slot for a MicroSD. You put the games on the MicroSD, put the MicroSD in the Flashcard and the flashcard in the DS. You choose a game through the menu and have fun with playing.

DS memory card?I assume you have a dsi, the memory card won't work like that, they aren't designed to.
In that case you need a flash card with "i" in the name, but DO AVOID r4 brand cards if you do buy a flash cart.Like an acekard 2.iAnd a micro sd card to save the games to (the one's for mobiles).