There are two ways you can go about this. One is a phonetic transcription, which means you would spell your name based on its pronunciation. "Keyden" would be the corect way to phonetically transcribe it.

The other way is an orthographic transcription, which focuses on keeping the spelling rather than the pronunciation. This would simply be "Kaden". It would be pronounced something like "Cadden", with the a sound in cat.

However you do it is up to you!