We not responsible for any damaged device, but we'll try to help you.
INSTALLING CUSTOM ROM WILL VOID THE WARRANTY.
Download the files:
Download ClockWorkMod (CWM) for your device (Google), rename to "CWM.zip", then place to your SD Card
Download the suitable ROM for your device, you can search this website, or Google. Rename to "ROM.zip". then place at your SD Card
If your downloaded ROM don't have Google Apps, you may need to download it too, rename it to "GoogleApps.zip" and place at your SD Card. Google Apps contains "Market, Gmail, and more". Download Google Apps here
Prepare the files:
Boot into Recovery by pressing Center Button and Power Button together. If the SAMSUNG logo appear, release the power button, but still press the center button.
Use the Volume up and down button to highlight, Center Button to choose.
Choose Update zip from SD Card. then, choose CWM.zip
Turn-off your phone.
Boot into Recovery again by pressing Center Button and Power Button together. If the SAMSUNG logo appear, release the power button, but still press the center button.
if you want to backup your data, choose Backup and restore. If you don't, skip to Install the system.
Choose backup and wait until the process done.
Install the system
Boot into recovery.
Choose wipe data/factory reset
Choose yes - wipe data/factory reset
Choose Install zip from SD Card
Choose choose zip from SD card
Choose ROM.zip
Choose yes - install ROM.zip
For ROM don't have Google Apps: choose choose zip from SD card
For ROM don't have Google Apps: choose GoogleApps.zip
For ROM don't have Google Apps: choose yes - install GoogleApps.zip
Go back
Choose reboot system now.
First-Run
First-Run of some ROM need a long time. so, please wait
Any questions? ask on forum or comment