How do i paste two sound files end to end?

I have a voice recording, and i would like to attach an mp3 right after it, so it can be on the same recording/file. No idea how to do this

Let’s assume you have two sound files. File > Import them and they will appear one above the other and play at the same time. You can use the MUTE and SOLO buttons to the left to hear each one by itself.

Select them both by shift-clicking just above each MUTE button. Tracks > Align Tracks > Align End To End. That should shove one track after the other.

When you Export them, they will become one simple track. Export. Audacity will not Save a sound file.