Attatchment management

Hi Eugene ...
I need some guideline about the management of the Attatchemnt files ...
I didn't attatch anything, only I have a few PDF invoice BUT ... how can I find them? Where are there?
Is it possible to make a single folder I can CLEAN time by time, with other folders inside ...
I do NOT want to upload to much stuff to my DB ...
Already like this is araund 100 MB ... If I load there all the files ... wooow. Bye Bye Space!
Thank You!
Pietro