This is mild chondromalcia patellae and following would help you;
1) Knee care in the activities of daily living. Few simple self-care measures can be remarkably effective in ending pain cycle.
a) Avoid prolonged standing or walking or sitting with joint in a single position.
b) whenever you sit, keep the knee stretched and fold them intermittently.
c) Squatting, sitting cross legged should not be done.
d) Avoid climbing stairs.
e) Avoid sitting legs unsupported or hanging.f) Reduce weight if over weight/obese.
2) Rest: Taking a break from your normal activities reduces repetitive strain on your knee, gives the time to heal and helps prevent further damage.
3) Anti-inflammatory medications
4) Physical therapy; the goal of physical therapy is to strengthen the muscles around your knee and help you regain knee stability. Ideal is supervised physical therapy. Stretching exercises are also part of the physical therapy regime.
5) Orthotics and bracing.
7) Hyaluronic acid injections in knee.
8) Local analgesic sprays and ointments to your skin may help relieve the pain and stiffness of osteoarthritis.
9) Deep Electrotherapy by physical therapist.
These are the exercise resources for the knee. You can pick the exercises which suits you;