A metal futon bunk bed often comes with the bottom bunk as a folding couch. This creates flexibility and good use of space you won't see even in similar space-saving furniture like bunk beds and loft beds. The folding couch mechanism makes these beds a little more complex to put together than other options, but this is no more than a one-hour project. Different models may have different quirks, but most manufacturers use similar general assembly methods.
Set the seat and back sections of the couch support on the ground. Push the edges together so that they nest, with the connecting holes aligned. Attach them using the cottar pins that came with your kit.
Attach the sliders to the edges of the seat and back sections, if not already in place. Set the couch support aside.
Lean one end piece against the wall, grooved panel facing inward. Attach the spacers - the front and back rails - of the futon couch to the end piece. Tighten the attaching bolts 1/4 to 1/3 of the way. Some models include a cleat in which to rest the spacers, others bolt them directly in place.
Set the opposite end piece in place and attach it to the free ends of the spacers, the same way you attached the other ends.
Set the frame for the upper mattress in place. Attach it according to the manufacturer's instructions. This is likely to be very similar to the method you used to attach the sliders below.
Slide the futon couch into position by settling the sliders into the grooves of the end pieces. Finish by tightening the connecting bolts fully.
Many models come with additional components like shelves, safety rails or a ladder. In most cases, these will attach using the same methods you used to attach the primary components.