Click on the circle next to Decrypt in the Options group. This will change some of the labels in the MEP dialog and disable the Create Self-Decrypting Executable option.
Click on the ... button next to File to be Decrypted field. This will display the Open dialog box. Browse your hard drive for the MEP-encrypted file you want to decrypt. Press Open when you've found the file. (If you know the name and location of the encrypted file you can just type it into the field directly.)
Next click the ... button to the right of the right of the Decrypted Output Directory field. This will open the Browse for Folder dialog box. Highlight a folder and click OK. The files stored in the encrypted archive will be created in the folder you choose.
Put the cursor in the Passphrase field and carefully type the passphrase used to encrypt the file. If the passphrase is wrong you will be given a warning and the program will exit. You'll need to restart the program and try again.
Lastly click the Start button to start decrypting the MEP-encrypted file.
(If you are decrypting files using an MEP self-decrypting executable follow steps 3-5 above.)