how to replace a light?

I have moved into my house and at the top of the stairs there are two fixings. one has a normal light attached to it the other has just what looks like a where a light used to be. I have bought a new light fitting but looking at the connection it is not as simple as I thought. Just need a bit of advice. I think it is complicated because it can be operated from both the upstairs and downstairs switch. hope this makes sense.
The fitting has a strip of 8 connectors. these are set out in line and in 2 x blocks of 3 and 1 x a block of 2.
There is one red wire connected in the block of 2. In the centre block there are 2 red wires and one empty and in the 3rd block there are 2 black wires and one empty connection. There are also the earths connected to the casing.
The light I have bought is very simple with simply a live neutral and earth screw.
All i want to do is connect the new light to this connection. Please advise