Welcome to the forum,
the one molex connector is to power all the 200mm fans inlcuded in Level 10 GT, all you need is to connect the molex onto the PSU molex, then you should be fine. And the 8 pin ribbon is for your front I/O ports, you need to check your motherboard user manual to figure that out. There is a section in the motherboard manual that tells you how to connect these pins correctly, if the information is not on, please consult with the motherboard's customer service, they should be able to provide that information to you.