how do I populate a cell with data from another worksheet,
 

I have two worksheets, both with similar data. Say columns are Acc No, Acc
Name and VAT number. Unfortunately the VAT number does not correspond on
each worksheet. How can I populate 1 worksheet with the VAT number so that
the data is collected on one worksheet? I have tried VLookup, but I'm not
really converant with it so would appreciate any help.
Many thanks
Denise