This is the book you want to start with:
This is the definitive guide:
This is the "Cliff's Notes" for getting started:
Apogee Components has a huge amount of information available, both on their website and their youtube channel. All of that is well worth reading/watching.
RPE is great for theory and big rockets. You can find a copy here:
But for where you are now, these two are likely going to be more important at the moment: