The first step is to choose a song that you'd like to use as your ringtone at https://klingeltonkostenlos.de/. You can search for ringtones online, or you can download a free mp3 file from a website and save it to your phone. It's also important to choose a ringtone that matches the style of your smartphone, as well as the person you're sending it to. You should pick a ringtone that isn't too loud and that has a cool, high-pitched sound.