Go to
http://www.r4ds.cn/download/r4_v1.18_kernel.ht ml and download the english kernel from the bottom of the page.
Format your SD as FAT32. Do a complete format - it won't take long.
Unzip the contents of the English folder in the zip file to your SD card (ie the _DS_MENU.DAT and _DS_MSHL.NDS should be in the root of the card with the _system_ and moonshl folders)
You may want to create a !Roms folder to hold your nds files to keep everything neat and make it easy for you to update the R4 software if necessary in the future.