Social Waves needs the info of how many times you talk with each of your friends in order to make your graph (it only counts the total of messages per day, it doesn't read, analyse or send them). The best way of getting this info is using the backup file that you can download from facebook. The first time you open this app you will be asked for this file. Follow this steps to get yours:

Start session in Facebook.

Visit settings page.

Click in the 'Download a Copy' link. You will be redirected to this page:

Click the button 'Create my file'. You will be asked for your password and to accept some confirmations.

Check your email and you will see that you got a Facebook email. They tell you that your file is in progress.

Wait a couple of minutes (it shouldn't last more than 5 minutes).

You will get another email where they give you a link to the following page:

Click in 'Download File' button. They will ask again for your password and the file will start downloading.