After downloading, open the disk image and double click the application. Now you can click on Start Server.
The Status should be 'Waiting for a Connection...'
Auto Receive will not ask permission when a sender starts sending a file (JPG)
Auto Save will save the received file to the desktop using either the name provided by the sender or an internal counter. This will overwrite a file with the same name if already exisiting.
Start on Launch will enable the server to receive when the application is opened, without needing to click the "Start Server" button.