There are lots of FTP server softwares. Try EFT Server or Serv-U. Serv-U is free for 30 days, and might work in some limited fashion after that.. its a bit vague on their website and its been a couple years since I dealt with FTP servers.
Are you saying you do not want to leave your PC on all the time?.. If so then get yourself a cheap hosting plan (there are many) with a web hosting company for ~5 dollars a month and set up an ftp site like that. Will be much faster than most home based servers, unless you have a super fast internet connection at home.