How do you see the waveform in Reaper?
go into REAPER: Options --> Preferences --> Peaks/Waveforms. There are a few appearance options in there to choose from. Check out: "sample level waveform view".
What is waveform recording?
A waveform is an image that represents an audio signal or recording. It shows the changes in amplitude over a certain amount of time. The amplitude of the signal is measured on the y-axis (vertically), while time is measured on the x-axis (horizontally).