I think it’s sweet you’re learning how to support your friend! What kind of help do you think she needs? Would be loving for you to learn Transgender terms and the general overview. Check out: http://www.reclaim.care
They have a Queer and Trans 101 that would help you. Cisgender and Transgender are adjectives. So I could say I’m a Trans woman and you’re a Cis man(correct me if I’m wrong). Also the term you were looking for is “transitioning”, not “transgendering”. Again, transgender is an adjective not a noun or verb. My best to you on your quest to learn!