What can I expect during an active birth?

Depends! This depends on what you mean by "active birth." the standard of care in medicine is the "active management of labor" which just means correcting or acting on problems that may arise to keep them from leading to harm. For example, position changes for any signs of the baby's heart rate not being normal or using medication if the uterine contraction rhythm is too irregular. Talk to your OB dr!
Lots. Discomfort from contractions. Emotions at their peak. Staff that is helpful and concerned. Ask questions and communicate so you understand what is happening. And at the end the most wonderful miracle of all- a beautiful baby.