So, clear as mud Annie Pearl?

I thread mine like it is shown in the link that Vicky provided (from the back, towards the left), but I have heard that some quilters switch it around the other way and get better results. Perhaps the best answer for you is either, a) try both ways on scrap fabric and examine your stitches to see if it makes any difference at all, and if so, which you like best. Or, b) contact a dealer who sells and services the make and model of machine you have and get their advice and opinion.