This is a rehab program for injuries to the outside of the knee (LCL). If you have a minor injury, this program might be all you need. If you have a more serious injury, please seek the assistance of a physiotherapist. If you’re just coming out of operation, please follow your doctor’s advice (you can show them this rehab plan beforehand).
You might not be able to bend/straighten the knee completely at this stage. Make sure to only go as far as you can without invoking more pain. Your goal will be to move the knee within your range of motion as much as possible, to prevent it from going stiff. Today and for as long as you need, it will be all about going to the edge of discomfort.