Let me see if I can help.
This assumes only one farbwerk needs to be installed:

Scope of delivery:
1x Bezel, black anodized aluminum
2x Stainless steel bracket
12x Spacer M3
12x Countersunk screw M3
12x Nut M3
4x Screw M3
8x Washer M3

Attaching the farbwork to the bezel:
Use four of the "countersunk M3 screws" by sticking them through the center four holes of the bezel, with the screw head to the outside (front) of the bezel.
Then place a "spacer M3" on each of the four screws from the inside (back of the bezel.
Then place a "washer M3" on each of the four screws over the spacers from the inside (back of the bezel.
Then install the farbwerk onto the four screws with the connectors away from the bezel.
Then use four of the "nuts M3) and screw onto the four screws, thus securing the farbwerk.

Attaching the two bay mounting brackets to the bezel:
Then using 2 of the "countersunk screws M3", and two of the "nuts M3", attach the right side stainless steel bracket to the bezel, with the screw heads to the front of the bezel..
Then using 2 of the "countersunk screws M3", and two of the "nuts M3", attach the left side stainless steelbracket to the bezel.

Then mount the assembly into a 5.25 inch bay, securing it into the bay with the four "screws M3", 2 on each bracket.

The only caveat here is I have never assembled one of these items, I just looked at the pictures and what was provided, so... this may be wrong.