how do i put a game onto the R4

i need help pls someone..

I will assume you haven't extracted the .nds file from the .rar file you downloaded. You need to download WinRAR here is a tutorial on its use https://www.romulation.org/forum/index.php?topic=1663.0 once extracted transfer the file to your Micro SD card via a card reader then place it into your R4.