Important to know: you have the correct sequence of these parts take montierien to this case. Look at picture No. 6 on top of the product in Amazon site, but this is actually a model B not B-plus -. Nevertheless, in principle, the method is similar.
Here are my assembly instructions:
1) the first time (do not remove Perhaps as a test run), the protective film, but how are you going ...........
2) The short end parts for Ethernet / 4 USB ports with R-Pi bring together (the small 'feet' of course, below).
3) The long side with audio / HDMI / Netzeileingang plug into the end parts (with R-Pi still there!). Tip: First pour in the upper tab into the hole, then the bottom tab (with slot) presses carefully and enter the hole.
4) Bring the other long side in addition to the GPIO pins together. As before, upper tab first, then lower tab. Caution! This page can go in both directions. The right way is with the little U in the top of the next end with USB ports (with equal with the U in the top of another long side).
5) Not the other short side !! That would be logical but not right !! First, the lid mounted, with its two small pins as a swivel joint on the same side as the short micro SD card. Fold with the two large tabs with the obengennante U's meet.
6) Then, the short end of the SD card (with mounted 'feet' down!) At last. Slowly and Accurately and press together with not so many power.
7) Finished! It may be that it is very difficult to enter the SD card and ausnehemen. Down (approx 15mm wide x 4mm high) remove 1) use a stick of ice cream (eg Magnum), or 2) first dismantle this end, this small piece of plastic with a mini-handsaw instead of a hole but - Two solutions to have a great U.
Have fun with it! Hope this is helpful for someone.
One more thing: the Raspberry Pi Foundation are loud, the thermal module (heatsinks) not necessary at all, and under no circumstances should one use. Just throw away or wear on your forehead !!