Excel 2007 : Finding/Matching data across two workbooks

Hello, need help urgently please.

I have two workbooks. First book contains billing details and amounts including a unique reference number for each row. Second workbook contains all the amounts paid against these unique reference numbers. I need to find the matching reference numbers across the two workbooks and then bring the paid date field from the row the reference is found on, from workbook 2 to the original row on workbook 1.

Any help will be appreciated.

Have a look at Vlookup() in Excel's help file.