How do I ride when my knees are like rice krispees and being on top is always painful? 30+years old F.

I am extremely inexperienced and only been with my ex husband and I was with him since I was 18. Im dating someone new and he talked about how he wants me to ride him because he wants to see me on top. My knees Crack so much and I haven't been on top of a man in like 6 years. What do I do? My pelvis is also tilted in a weird way so being on top is never pleasurable for me so im only really doing it for him. I want to be good at it so I can get him off as quickly as possible since it will be painful for me (its nothing to do with lube or his size and everything to do with my awful pelvic anatomy)