After launching Audacity, go to the File option, and select Open or Import to import the audio or video file into Audacity. Audacity will remind you to make a copy of the audio file before editing. I think this is very caring. However, if you're importing a video file to Audacity, you may need to first download and install FFmpeg Library. Otherwise, you need to detach the audio from the video or convert the video to audio to compatible formats.