This is an example of how to mount:
You'll have to connect that 1 PCI piece on your motherboard them connect via USB to the 3 PCIe piece
For power I strongly recommend to use molex instead of sata, never use Sata cable to power, and avoid to use converters like Molex to sata
Another piece, the green one, is to use 2 PSU, that piece will make your 2PSU start together with primary PSU
It's important to know that this PCI 1 to 3 PCI will not work on all slots and all motherboards, there's some incompatibility.