That is a very broad question, so let me give you a few ideas and a few websites.
First, you need to protect the skin on the rear legs from getting sores. Urine that is left on the skin can be very irritating and cause severe skin wounds. You will need to learn to express the urinary bladder if they are not able to do that themselves. Sometimes that is easy and sometimes it is not.
Here is a website with a lot of good information for you.
http://www.dodgerslist.comHere is their section about incontinence.
http://www.dodgerslist.com/literature/IncontinentDown.htmThis website has a number of good products to help you. You may want to purchase products from them or make your own based on their ideas.
https://www.handicappedpets.comGood luck! I hope that gives you some ideas and was helpful. Please let us know if you have any other questions. Thanks for using PetCoach.