Go to "Toolbox" > "Ringtone Maker", then you will see a pop-up window like this.
If you want to make a ringtone from your iPhone music, then go to "Add files from device". If you want to create a ringtone from the song stored in your PC, then choose "Add files from PC".
Add Files from Device
Select a song from your device and click "Select" button.
Now you can start making iPhone ringtone. You can set the starting point and ending point manually. When all is done, click at "Generate" button to make your ringtone.
Add Files from PC
Select a song from your local folder and set the starting point and ending point of your iPhone ringtone. If you want to transfer the ringtone directly to your deice, please make sure that you have selected the "Add to device" option.