i REALLY need help

ok so im not a high tech kind of person and i have no idea what your talking about when reading your tutorials. can someone explain somethings to me. i got the r4 card, i downloaded some games, unzipped the files, but every time i drag and drop the games into the sd card it says that the file is to large. i was told i could get at least 40 games with the sd card i have. is there something im going wrong? if this makes a difference i have a mac, not a pc.
please help ???

Insert the SD card in your computer, right click on it in explorer and choose format. Click start and it should start formatting your card, once done, place the R4 firmware either from the official site or from http://www.linfoxdomain.com/nintendo/ds/ on your SD card. Create a games directory and put your games in there.