Help please for a novice

I have just downloaded some games for my son, they copied to the sd card fine but when i look for them on the ds they are not there. I would be gratefull for some help

The games here come compressed in an archive called a RAR file.This makes them smaller files to download. But you have to decompress the files before you can use them.Read this tutorial for step by step instructions:
https://www.romulation.org/forum/index.php?topic=3880.0