Learn about donation. It is such a general question. I encourage you to visit the National Kidney Foundation's website on living donation: https://www.kidney.org/transplantation/livingdonors.
Live kidney donation. If a friend or loved one needs a kidney transplant you can go with them to their transplant center and be evaluated for your tissue match, as well as for your own risks based on your medical history.. If you qualify, the kidney is removed with a small incision and with little trauma or risk to you. There is a small risk of living with one kidney, but you can live a full life with only one.
First find a donor. You need a healthy donor who matches you. Next the donor kidney is removed at the same time as your surgery is started. They are done in different operating rooms. The donor kidney is the transplanted in the same manner as a deceased kidney. The kidney can be removed laparoscopically or with an open surgery.