Cut soap base into 1' square blocks and melt in a double boiler or the microwave (if you use the microwave, heat in 30-second increments, mixing between heating sessions).
Remove from heat and add skin-safe essential oil or fragrance oil to your liking. A good rule of thumb is to start with 1 tsp of fragrance/essential oil for every 16 oz of soap base you use, and go from there. Be careful not to over-use fragrance, or the soap won't solidify properly.
Add a few drops of gel tone colorant* and mix; add more drops until you achieve the desired level of color.
Pour into molds and let cool. After a few hours, the soap should be ready to pop out of the molds!