Need help with upgrading firmware.

I couldn't get GRID to work so someone told me to go to this site http://www.linfoxdomain.com/nintendo/ds/ and i downloaded the firmware now what do i do with the file. I use r4 ds by the way. I would apreciate it if anyone can help me.Thanks

Extract the archive. If there is a language folder, go into it and take all the files/folders in there out. Replace all the previous firmware files with the new ones you just downloaded on your MicroSD etc. Make sure to get the Confirmation message.