Kandrew,
Start and End are the starting and ending character position. They are optional inputs, and I believe if you don't wire them the picture will be added to the end of the document.
To ensure that it is attached to the end, you can use the Range.End property, and then use another Document.Range method. End-1 will be the Start point.
Another idea is to paste picture at a bookmark. You would use Document.Bookmarks property to get a reference to Bookmarks object. Then wire bookmark name to Bookmarks.Index method. Wire Item reference output of this method to Bookmark.End property. This End output number wire to both Start and End inputs of another Document.Range method.
Zvezdana S.