Overdubbing or adding a track

Hello. I’m using Windows 7 with Audacity version 2.1.2 .exe installer. First, thanks for the program. All the tutorials are quite helpful and make this very user friendly. Can’t seem to find anything on this though. Overdubbing or adding a track. I record the initial first track on guitar. The second I am trying to record vocals through a microphone using headphones so no other sound gets through on the mic. I have the initial track playing while I record the second in order to stay in time. The second track is recording the vocals but it is also recording the first track onto the second track at the same time. The first track still remains guitar only but the second track records both tracks. I would like to keep the vocals separate from the guitar on two different tracks. Is this possible? Thanks.

Ensure that your microphone is selected as the recording device in the device toolbar (not the “Sound Mapper”).