How to use a microphone to record a story
Most laptops and computers include a mic today, here's how to get started
When you click the mic button to contribute to a Ponga picture, the software will prompt you for access to any attached microphone. If you have one connected via the headphone jack or a USB port, your computer will default to that one.
Generally, this is controlled in your computer Sound settings. On a Macintosh, for example, the Sound settings displays, or allow you to select, the device that records your voice input. Windows computers and Chromebooks have similar settings.

Like an audio/video setup for Zoom, FaceTime, or Skype calls, there's a wide selection of wired (USB or mini-phono connected) and wireless (usually Bluetooth), equipment available. Your selection will vary depending on your budget and quality requirements.
If you find you need one, you can search for relevant reviews for mics used in mobile, gaming, and podcasting applications. Any of those can be used with Ponga. Just plug the equipment in as you would for those apps, and click the record button. Your browser interface may ask you to allow the mic to be used, but that's about it.
One thing to consider: If you expect to be recording your own voice telling stories, then a headset/mic combination can work quite well. If, however, you expect to be sitting with an elder parent or grandparent so that you operate the computer but it's their voice that's recorded, you might consider a headset they're comfortable with or using an external mic like the Blue Snowball iCE, and even adding portable Bluetooth speakers if you're visiting them in their home or residence. The elderly can be hard of hearing and earphones often don't work well with hearing aids.
If you'd like to record, then edit, or mix your sound, that can absolutely work with Ponga. You would add pre-recorded sound to a comment a little differently, however. For a discussion, see the article Can I upload a pre-recorded sound file.