After downloading, go to recovery mode and do as I say:
1. Format/wipe data partition
2. Format/wipe cache partition
3. Go to advanced options and wipe dalvik cache.
4. Go to install zip
5. Choose zip from your SD card
6. It'll open an aroma installer
7. Click on continue on the first page, choose your language
8. For the theme, choose any theme and continue. After installing, it'll auto reboot itself Sit back and relax, first booting takes time.