How to open .rar files?

Hi guys just done my r4ds and turn on the power, i get a list of games, but when i try to play them it says "these types of files are currnetly not allowed" pLease can anyone help. Thanks.

Re: NDS ROMS DOWNLOADED FROM HERE ARE .RAR FILES. BUT DS DOESN'T RECOGNISE THESEget teh most recent firmware also make sure you extract the game from the .RAR file which is like a zip file if you do not have a program that works with extracting fom .RAR i recommend you search windows .rar thats what i did to get a freeware version of the program

Re: NDS ROMS DOWNLOADED FROM HERE ARE .RAR FILES. BUT DS DOESN'T RECOGNISE THESEOk. Thanks alot mate.

Edited to make the topic slightly more readable.