help for costing ca final

Could anyone please tell me what should i do for costing? i had given my attempt in nov 2010 old course.But i cudnt clear.

now i have to give exam in new course.How do i prepare for this subject? i am just not gettg it.in the nov exam i just cudnt manage my time and in that process the paper went hotch potch.some questions i cudnt understand also.

what shud i do??? pls help