Decrypting files is really easy with File Obfuscator's GUI (Graphical User Interface).
All you have to do is follow 3 simple steps:
1 Find the obf file you want to retrieve and type it's path in the File text entry
2 Retype the password you used to encrypt it and type it in the Key text entry
3 Click the Scramble button
You will get a new file in the same folder with two obf extensions whose contents is the same as the original file (provided that you entered the same Key).
The xor operation used to scramble the files is symetric meaning encryption and decryption are the same process. For a more detailed explanation refere to the same section of the Encrypting files page.