to use any custom rom you need to root your phone first
use Universal Androot and its soo easy-download it from GingerBreak
1.download the apk file
2.use file explorer installed on the device,and install the GingerBreak
3.and then simply click root and.... Now your phone is rooted.
Download GingerBreak: http://forum.xda-developers.com/show....php?t=1044765