Where do addons go in Silent Hunter 3 files?

Hi everyone.
I need some advice & help please.

I have not long brought Silent Hunter 3 and am learning the in's & out's of it.
I have,or will be downloading some add on's,such as weather,extra ships,well just about everything that I can.

My question is where in the Silent Hunter file do I place these add on's?

Any advice or help would be appreciated.

Thanks everybody.