Hi Anna Mitchell. I've attached some videos that should help with your knees. In addition, you can look for low-impact exercises. You may want to try some videos by Angelo Dela Cruz. He has a lot of good ones on mobility. You also may want to try some low-impact yoga classes. Here's a link to the "Pain Relief Yoga": https://grokker.com/search/videos?topicid=4fcd354b46ec474e2e000002&filters=topicids_55a0271f0289054b2e092530%3D%257C4ffc52828f43beb72a00015c
Hope these help!