To record a voice over in ProShow you need to double-click on the slide and then click on the ‘Slide Sounds’ button located under Backgound + Sound. Click on the ‘Record’ button found near the top left-hand corner of the Slide Sounds to begin the recording.
ProShow allows you to record a slide sound directly from within the program. Most people use this feature for narrations, however you can also use the slide sound option to add sound effects. To add a sound effect to the slide, click the ‘browse’ button to load the sound effect into the slide.
Check out the video below for a visual walk through.