I recently purchased the software Sonar Proffesional. I just set up my recording interface. When I record one layer it is fine, but as soon as I start to record a second layer and re-records the layer that is playing back to me so I know what to sing along to. 
 
Can anyone help me figure this out or even give me some starter tips as I have never used this software or recorded myself before?
 
Thank you in advance!

Are you adding a second track for the second pass?
 
Each track has an input and an output.  Do both tracks have the same input (set one of them to 'none').
 
are both tracks armed (small red button on track)?  if so, turn the arming off on the first track.
 
If you are recording into the same track, right click on the record button and select 'Sound on Sound).  This will probably do what you want (which is probably not what you really want).
 
Glen
 
 

Hello  curley,
 
I'm not quite sure I understand your question. If you want your first recording to play while you sing into a second recording, you would record your 1st take on track 1 and then your second on track 2. Is that what you mean?
 
If you are new to Sonar you should take some time to watch some of the videos on Cake TV. They can be helpful. I also highly recommend Groove3.com. They have a great set of videos on Sonar. You can either buy one or sign up for a month and view all the videos you want for that month. It might be very helpful.
 
Dave

If using an onboard soundcard, set the Input in the soundcard's mixer app to Line or Mic In. If set to What U Hear or Stereo Mix, you are recording from the output, which is why it re-records the first track playing back.
 
 

So my issue is I am recording through a mixer, lets say I record me playing guitar for the song. After recording that section I go to record in a new track below it. but what happens when I record me singing, the program re records the guitar layer as it plays back. So essentially I am recording the guitar in one recording, if i were to make a new track, press record and just listen to the guitar play back whilst in recording mode the guitar will double over so there is a recording on the original track and then also the exact same recording on the new track.

Use your audio interface for monitoring. It should have a mix or blend control so you can balance the DAW output with your input from the mixer. 
If you don't own an audio interface yet then start shopping. Modern DAW software requires a proper audio interface to function smoothly. 
If you send your audio output to the mixer for monitoring you will have to configure the mixer properly. Without knowing the equipment your using it is hard to give a solid answer.  

It sounds like the first track is always armed for recording.
 
It is only going to record a track that is armed.
 
When you record the 1st track, the guitar, arm that track for recording, then record the guitar track. Disarm the first track, then arm the second track and record yourself singing.