How do i download my songs from my iphone 5 to my new macbook pro so i can listen to them on itunes?

If you do not have access to the iTunes Library on your Old computer... or its Backup...

See these 2 Links...

Syncing to a New Computer...

https://discussions.apple.com/docs/DOC-3141

Recovering your iTunes library from your iPod or iOS device

https://discussions.apple.com/docs/DOC-3991

If you do have access... See Here...

iTunes: How to move your music to a new computer

Or...

From your OLD computer...

Copy your ENTIRE iTunes FOLDER to an External Drive... and then from the External Drive to your New Computer..

Full Details Here > http://support.apple.com/kb/HT1751