When preparing statement of cash flow . what is the information required to prepare it ?

Income statement that  based on cash transaction not on accrual based.

Find out Cash & Non-cash transactions from the reported Income statement, 

Just remove the non-cash transactions from the Income statement, that is it your cash flow statement is ready.

All you need to know finally is the formatting of the cash flow under the three categories (Operation Activities, Financing Activities & Investing Activities)

most important balance sheet/income statement and other adjustment entries depend which activity statement you are going to prepare operating activity, investment activity or financing activity.all three needs different information.