TL;DR: Nobody here can answer your question
If you're experiencing enough pain that you struggle with simple tasks like navigating a set of stairs, you should see a physician. At the very least, they will recommend rest and ice (which you should do in the meantime anyway), and they will probably give you a referral for physical therapy. A physical therapist can give an answer to your question that is tailored to the specific nature of your injury.
If your financial situation or a lack of insurance precludes you from seeing a doctor, then I would once again recommend rest and ice, and avoiding activities that cause pain whenever possible (use an elevator, take weight off of your bad knee by leaning on a sturdy railing, etc.).
To answer the question that was actually posed: the knee is a very complex joint - even an expert will need more information than you've provided to give you an answer. Leaning either forward or backward could cause more stress on the injury depending on what the injury actually is.