REAPER is a digital audio workstation (DAW) built around flexibility. You can customize its shortcuts, menus, toolbars, and mouse behavior, but its defaults are enough to get started.

Show or hide the mixer with Cmd + M on macOS or Ctrl + M on Windows.
Cmd/Ctrl + T, or double-click below the last track.Delete.Put two media types on one track. Then create a folder that contains several tracks.
Right-click on your timeline to change its units.
Find a few sounds on Freesound and drag them into REAPER. Watch the track names and the way items snap to the grid. Use the magnet button if snapping is off. Press
Spaceto play or stop.
Shift while dragging to ignore snapping.Cmd on macOS or Ctrl on Windows while dragging to copy an item.X.R to toggle repeat playback.S to split selected items at the edit cursor.F2 to open item properties.Shift while moving an item to ignore snapping.- and +.Cmd + wheel on macOS or Ctrl + wheel on Windows.Option + wheel on macOS or Alt + wheel on Windows.W to jump to the project start. Press End to jump to the project end.
Cmd + M on macOS or Ctrl + M on Windows. Dock it in the main window or float it on another display.Cmd/Ctrl + wheel to resize tracks.Page Up/Down also work on full-size keyboards.? to open the Actions list.