Selection.InsertColumns (Word)

Inserts columns to the left of the column that contains the selection.

The number of columns inserted is equal to the number of columns selected. You can also insert columns by using the Add method of the Columns object. If the selection isn't in a table, an error occurs.

If Selection.Information(wdWithInTable) = True Then 
 With Selection 
 .InsertColumns 
 .Shading.Texture = wdTexture10Percent 
 End With 
End If