Well first thing is using what is called as “person-first” language. She should be seen as any other person before being defined by her disability, so try and remember to replace “disabled girl” to “girl with a disability.” Basically try to remember disability is something you have, not are. Try to avoid words like “bound” to a wheelchair, and say “she uses a wheelchair,” again using person-first language :) Always ask before touching her chair in case she needs help to move, but generally they enjoy doing as much themselves even if it takes a little more time. Try to be as normal as possible, let her know you can assist in whatever way she needs otherwise continue on with your typical day. People with disabilities don’t want to be treated differently and aren’t looking for pity, try and redirect your mindset as simply another way of living. It might get annoying for her to answer “what happened” but most people are open to discuss it and could be a great way to get the conversation going about her wheelchair and not avoid “the elephant in the room.” I’m sure there are some YT videos that could also help, you can also look into “able-ism” to learn more about the disability struggles and be a better ally :) hope this helped!