This video by @jason-mccreary is a good jumping off point - he does a good job explaining the mindset of testing your code. If you follow him on Youtube, you will see there are a number of videos covering TDD.
From there and more specific to Laravel, you have the Testing Laravel course here on Laracasts, and the Forum series
I would also suggest that you learn PHP as well, and feel comfortable with it before you jump into testing. PHP Practitioner here on Laracasts is a good series for that.