Cant import new track for editing purposes

Hi
I have two pieces of audio I want to edit together but cant get one of the tracks to open in the same screen as the other. When I click file>import>audio and select the file I want to import I get the message ‘XXXX is an Audacity file. Use the File>Open command to open Audacity projects’. Both are recorded in Mono. I’d appreciate any help you can give thanks !

file I want to import I get the message 'XXXX is an Audacity file

Is it an Audacity AUP project file? If so, open it separately and export to WAV. Then you should be able to add the WAV track to your existing project.

Thanks that worked, but the levels are totally different now and the WAV file is very distorted. How can I change that? thanks

Each track has gain-slider

which controls the level of that track.
When you add a track to a project you’ll probably have to turn down all the track gain-sliders to avoid distortion.