There was a number of typos in your snippet, but here a clean working example :
#include <Word.au3>
Local $oWord = _Word_Create()
Local $oDoc = _Word_DocOpen($oWord, @ScriptDir & "\V.doc", Default, Default, True)
$oSearchRange = _Word_DocRangeSet($oDoc, -1)
$oRangeFound = _Word_DocFind($oDoc, "Dijon", $oSearchRange)
$oSearchRange = _Word_DocRangeSet($oDoc, $oRangeFound, $wdParagraph, 1)
_Word_DocPictureAdd($oDoc, @ScriptDir & "\Pic1.jpg", Default, Default, $oRangeFound)