You can only monitor what you record if you have configured the track you are recording on with ASIO compatible hardware. So you need to install ASIO4All if you do not have that installed and make sure the recording device you are using is compatible with ASIO. Each track has a wrench icon in its controls, make sure to click on that and Under the recording options section make sure you have set the correct device with ASIO. You should then be able to monitor the track while recording.