The small white soapstone after a short amount of time gives you a smooth and silky for helping another worlds master. The white sign soapstone which is located in the forest of giants can be obtained after clearing an area you get locked in by an NPC who is sitting in front of a gate. Clear it and talk to him he will give it to you. Both soapstones have a time limit, the larger one obviously being a longer amount of time 15min I believe. You join another worlds master to get souls from their enemies as well as the boss once you clear it. Aside from souls it will turn you back to a human as well after beating it. Lastly their is two covenants in the game which, to earn the rewards, you have to help other players beat the boss of the area. Please feel free to ask any other questions :)