does it matter witch way I mount this heatsink to my mobo?

It's pretty irrelevant. You could orient the pipes to the outer edge of the motherboard to be exposed to more air and less surrounding components. It really won't make much of a difference, though.

There is usually one way to put it on correctly. They usually have a clamping mechanism to tightly secure the Heatsink on.

If you've never mounted one on, it's pretty easy. Make sure and clean the processor with some kind of processor cleaner (arctic silver etc) or use 90% or higher rubbing alcohol. Then get some new compound and put a drop in the middle. Then just mount it on.

I can't really see how that heat sink clamps on, but it looks like it is a simple clamp.

I have an almost identical Thermaltake & I was able to fit it by moving my RAM to a further away slot. You can you know. You may have to temporarily remove your case fan to get your fingers in.