To create the labels first move Edit > Labels > Add Label at Selection and take a look at the keyboard shortcut (Ctrl+B in Windows) in order that you don’t want to return to the menu each and every time.
Now that you recognize the keyboard shortcut make a choice a area in the spectrogram that you need to label (click on and drag) after which use the shortcut to ‘Add Label at Selection’. A label observe will seem and you’ll be able to sort the identify for your label. You can repeat this procedure to upload as many labels as wanted!
Note: It is helping to play the clip as you might be labelling. You can use the ‘house bar’ to play and pause.