Downloading ds games

Hi there I am new to this can anyone help??When you have down loaded one of the rar files how do you get it to work on the R4 card ???
I have tried extracting it but have never got it to work..

Extract with a program called winRAR (Google "winRAR" to download it).Once extracted with winRAR, you will find a .nds file. Put that .nds anywhere in your MicroSD card so you can play it on your R4.

Have tried it again this morning and it went through first time so many thanks!!!