Just create one. Simple plain text file named "parallelcoin" with extension "conf".

The location of parallelcoin.conf depends on your operating system:

Windows XP

C:\Documents and Settings\\Application Data\Parallelcoin\parallelcoin.conf

Windows Vista, 7, 10

C:\Users\\AppData\Roaming\Parallelcoin                                             

Linux                       

/home//.parallelcoin/parallelcoin.conf                                                           

Mac OSX

/Users//Library/Application Support/Parallelcoin/parallelcoin.conf