HOw do I put a label or mark directly on a home made soap? Let say I want it marked as GRACE. How can I place the mark directly on the soap bar so that the brand name can be recognized even without the package or the wrapper?

Pour the soap into a mold that has the word GRACE in relief on the bottom. When you take the soap out of the mold, voilà!

If you didn't mind the label not being very deep, you could also have a plastic or metal stamp made with the design/words of your choice, whereby you could impress this stamp on the bars of soap while they are still somewhat soft.