I haven't got this kind of mount but are the sides of the bar that was attached to the scope in picture one angled rather than at 90deg? If so, then that's most likely what goes into the mount (the bottom bit in picture two) and you tighten both bolts to make sure it doesn't slip out. Somebody with a bit more expertise will probably be along to confirm soon. I know what you mean about it being frustrating, it's a steep learning curve and I'm still finding it complex. But the first time you see a planet with its moons or a double star, it'll blow your mind and it'll all be worth it. This forum is a great place for getting advice, don't hesitate to ask questions, they're very gentle with us beginners