To set a custom ringtone for incoming calls on your phone, you can follow these general steps:
1. Open the Settings app on your phone.
2. Look for the "Sound" or "Sound & Vibration" option.
3. Within the sound settings, you should find an option for "Ringtone" or "Phone ringtone."
4. Tap on this option to select a new ringtone from the list of pre-installed ringtones on your device.
5. If you want to use a custom ringtone that you have downloaded or transferred to your phone, there should be an option to choose "Add ringtone" or "Select from device storage."
6. Navigate to the location where your custom ringtone is stored and select it to set it as your incoming call ringtone.
If you need specific instructions for a particular type of phone or operating system, please provide more details so I can give you more tailored guidance.