From another thread, I gather that you know how to drag files into the timeline, so:
- Right-click in the timeline area and Add Video Track.
- Right-click in the timeline area and Add Audio Track.
- Drag your video to the video track and audio to the audio track.
- Click on the Export button in the top toolbar.
- Select a preset, then click the “Export File” button (which might be hidden on small displays).
Does that help?