Hi Debbie,
This type bobbin case can be a pain to get back in. On photo #1, at the top left you see a silver piece (circled in red) with a rectangular hole in it (circled in green)...take a flat head screw driver and insert it into the slot then twist to the right so the little bar/flange (circled in blue) will twist to the left past the bobbin well wall (marked in neon green). Photo #2 Now the bar/flange (marked in blue) should be on top of the bobbin well wall (marked in neon green). Now set the bobbin case in the bobbin well (marked in pink). Photo #3 as you set the black bobbin case in, kind of angle the flat part that is marked by the orange X so that it will begin to underneath the bar/flange with large orange circle. It won't go in all the way but just start it and then set the rest of the case down in the well. Now twist the entire black case to the right and the flat black are marked with the orange (X) should slide underneath the bar/flange marked with orange circle. The flat piece marked with a purple (X) should be sitting in the area marked with an (X) in the bobbin well. Now take your screwdriver and stick it in the rectangular box and twist it back so the silver piece marked in blue with go back over the edge of the black bobbin case to help hold it in. Hope you can understand my instructions and good luck!