Help me, I'm a beginner!

All I want to do is take several mp3 files and add them together with a little cutting and editing on the way to make one 9 minute audio file. I can import them fine but now none of the editing options are available to me. What am I doing wrong?

Please state which version of macOS you are using,
and the exact three-section version of Audacity from “Audacity menu > About Audacity”.

Double-click the downloaded DMG to mount it.
Drag the “” icon in the DMG window to the /Applications folder icon on the right. Alternatively, drag the “” icon to any other location of your choosing.
Do not double-click the “Audacity” icon in the DMG to launch Audacity from there.
Eject the DMG at bottom left of Finder, then launch from /Applications or from your chosen location.