Install and Open terminal Emulator n apply following commands one by one.('Enter' after each command )
(Terminal emulator From Google Play)
Without quotes
"su
mount -o remount,exec /dev/block//vold/179:1 /sdcard
cd /sdcard
./flash_image recovery /sdcard/recovery.img"
Put the zip to root of sdcard, rename it to CWM.zip(not necessary though)
Power off the phone, boot into recovery by holding volume up + power on.
Now select, Install zip from sdcard
Choose zip from sdcard
Select your CWM.zip file
Confirm and U r done.