How to attch a word document to Purchase requisation ME51N

Hi

I am facing a problem to attach a drawing document or word document to the transaction ME51N how I can attach a document for purchase requisation, when I tried to click attch document in item overview sub menu bar . one pop up screen is coming in that it is asking Document type and document part and version , where i can do the customising attach the document .

can any body help me to get the solution .

Thanks in advance

Srinivas .Rangi