I shall tell you, and you can also just put it in search on your computer.
Get a bottlee of castor oil. Take a good sized piece of wool flannel. or if you order from Walmart on line they have the material & the oil on the same page. Soak the wool in the castor oil. Lay it on a bigger piece of plastic because castor oil will stain. Take your heating pad set as warm as you find comfortable, and place the oiled cloth on the area you wish to treat & cover with the heating pad. Tie with an ace badage if necessary unless you'll be lying on it. Treat for an hour to an hour & a half. and for or two more days if necessary. Wash the area treated with Dawn to remove the castor oil. You can use it over & over kept in a plastic bag & refresh at some future date.