Error occured while flashing Galaxy Y with JELLYBLAST V3.0.2
This error comes normally for two reason. 


You have a corrupted .zip so you should try re-downloading.
You have an unsupported recovery. 


According to your ROM's requirements, You must have stock kernal. Most of the time while rooting, we flash a different kernal. So you may have to flash your stock kernal back again.
And also you must have a CWM recovery, as they say.  You can find it here http://techcure.wordpress.com/2012/10/17/how-to-root-and-use-cwm-for-galaxy-y-gt-s5360/ 

If you have already done these steps, please let me know. I will try to help as much as I can.