Since you said "Many thanks" I assumed you understood me. So sorry. Must hone my pedagogy!
The IMSLP products are all PDF's, and should open in Acrobat Reader. In Acrobat, you'll find different selection tools in the toolbar: a Hand that functions like a grabber. When you click and drag, you move the score.
There's a "select" tool that looks like a cursor, when you click and drag, you select text and it gets highlighted. Then you can copy and paste, etc.
Next to that is a snapshot tool, when you click-and-drag, you create a dashed-line rectangle and can create such around any snippet of score or some other graphic. When you finish dragging open such a rectangle, the imagery covered by its area is automatically "copied" to your clipboard. Don't ask me where your clipboard is; it dunna matter.
Then Paste the item into a Paint or Photoshop file, and save as a .pdf -- (which may be under the File... menu as "Save for Web page" or the like) -- it may also be in the Print...dialog box as "Save as pdf". It all depends on which program you use.
Armed with this .pdf, you can upload it to Photobucket so easily it will make your head spin. Though first you need a Photobucket account. Or use the r3ok Photobucket account, as described in the Announcements thread. Once this pdf is in principle a webpage, you can refer it with the img/img square bracket code that you're already familiar with from other walks of your autoharpic life.
I expect
results before my 35th birthday! Otherwise, I can't submit a mark for you and will be forced to give you an "Incomplete"