Click on browse and load your Crypt6 Crypt7 or Crypt8 files. You will then be asked to enter your key. So you must also load the crypt key from your computer. Backuptrans Android WhatsApp Transfer will then decrypt your database. When the process is done, you will find a screen similar to the one below with your contacts and your sent and received messages. You can then read all your messages just like they appear on your phone.
This is a trial version which allows up to 20 messages.