Hello there, I am new to this sub and I just wanted to ask how I can learn more about BPD?

I am currently dating someone who told me of her struggles with BPD. I myself also have been told by a psychiatrist I was seeing that I have some traits of the disorder myself. 

If I’m honest, I don’t quite understand fully what having BPD entails. I don’t know much and I really want to learn and be as supportive of a partner as I can possibly be too. 

Do you guys know of any good books, sites, resources etc where I can learn more? I honestly don’t know where to begin.