Unintentional Thought Vs. Intentional Thought

This is my first month in scholars. I must have missed it somewhere. I’ve been trying to read everything and watch everything and I am still confused. I still don’t understand the difference between an intentional thought and an unintentional thought. How do I arrive at each of these? Also, can you point me in the direction of what I need to watch or read to better understand? Thank you!