If she opens up, and she shares about some difficulties she's going through, imagine what that must be like for her, and then verbally remark about it in supportive ways that show you are giving her your full attention.
Like, "that must have taken a lot of strength to go through that" "That wasn't right of them to treat you that way" "Sounds like you've been carrying a heavy burden, I don't know many who would have been able to do the same"
Apply supportive statements that show you are listening.
If something comes up that is about someone doing her harm or someone did something to her that wasn't right, definitely mention that it wasn't right of that person to do or say that to her.
If she's sharing, you can carefully use some basic simple descriptions of emotions with your own statements about yourself, to show her it's safe to express emotion, in appropriate moments for you to speak (which really requires you to put her comfort and safety first, and is usually more a feeling of the moment - she'll let you know but it won't necessarily be verbally)
something like "oh wow, I would have been angry if that happened to me." "I respect how well you handled that".
Be careful not to push her into feeling, avoid statements that force her to experience the feelings.
You're there to make it safe and comfortable for her to share.
There will probably not be any sharing at first go. She may not trust that it's safe. If you feel like you did everything right, she still may not open up. That's ok. Even if you make the perfect safe space, it's still her decision on whether or not to share.
Do not get upset if she doesn't open up. If she doesn't trust yet, and you get frustrated because you thought you did everything right, that shows her it's not really safe for her and you're not really there for her.
Being there for her means respecting her wishes and boundaries, her decision to open up, or NOT open up.
Your goal is listen, make her comfortable and safe, and give support and be gentle. That's all you can do, the rest is up to her.
Make your focus on her. Make your focus on giving her a safe, comfortable, gentle, and respectful support, and really hearing her.
She will communicate with you, verbally and non verbally. If her body says "I don't want to do this" then respect that, and give yourself a way to gracefully give her space, something like "I'm going to go grab some water from the kitchen, want anything?"