When you click "Scan" button, phone will be read via USB. Please make sure that the Nokia conectivity drivers are installed properly. You can download them from the original Nokia website if you don't already have them. If you have use NSS before or have PC suite installed, the chances are high that you already have those drivers installed.
To read ASK file, you have to click "Read ASK" button. Data from phone will be read and you will be prompted to save the ASK file to choosen by you location.
To write RPL file, you have to click "Write RPL" button and select the RPL file or simply just Drag and Drop the file over the application.
Then the RPL file will be written in the phone