A Custom Firmware is a modded version of original Nokia Firmware. It gives you ultimate out of Your phone such as speed ups,sound boost new homescreens & more of everything.
To use a Custom Firmware we often come across terms like Flashing.To flash your you first need some basic softwares such as JAF, OEMPkey emuluter etc.to start flashing your phone get ready with these softwares & Original Nokia Firmware.Download these
http://www.mediafire.com/?3ker4ul1umflgpk --Original Nokia Firmware v21.1.102 newer
http://www.mediafire.com/?aimnjvtyvdjii3d --Original Nokia Firmware v21.1.004 older
Both of these are original but u have to use according to the custom firmware you want to use.
Almost all the latest mods are based on these two versions.
http://www.mediafire.com/?mudeyqowwc5r868 --Nokia Flashing tools pack