I love making glycerin soap or melt and pour soap. I recently found a recipe that I had used before for herb glycerin soap. Here is the recipe.
Fill a soap mold half full of glycerin melted soap. Add a sprig of rosemary or thyme to soap. Let set for about 15 minutes. Then fill rest of mold with melted glycerin soap. Wait until it cools and hardens. Then pop out of mold. You may color the soap when it is melted before it is poured into the mold. I think 2-3 drops of green soap color looks pretty on one of these glycerin soap bars.