How do i conver the file .rar to .nds to play on my dsi??

Please can u show me how to convert the files from a .rar to a .nds so that i am able to play the games on my dsi

https://www.romulation.org/forum/index.php?topic=3880.0
https://www.romulation.org/forum/index.php?topic=1663.0The search function is there for a reason.