How do I save MP3 song files to my iPad so I can attach them to Apple emails?

I use 100% Apple everything, since 1984: iMac, iPad, and iPhone. I don’t use Google Drive.

i’m disabled and I don’t currently have access to my iMac.

My Music Library contains a thousand versions of my own songs — songs that I composed and performed and recorded myself.

i’m currently on WiFi and fully Synced.

How do I save MP3 song files to my iPad so I can attach them to Apple emails?

[Re-Titled by Moderator]