Get some of the white chocolate coating wafers or white choc chips. Melt them and dip the ghosties into them. If you have lollipop sticks or wooden skewers they make fun lollipop type treats. Add 1-2 tsp all vegetable shortening (Crisco or house brand, MUST be all shortening - NOT butter) as you melt the white chocolate to make it stay shiny. If you use the coating wafers you don't need the shortening.
If you want to color the white chocolate you need to use an oil based coloring or buy precolored coating wafers. Even the small amount of water in food coloring will make the coating seize up and useless. on the other hand, if you just want to color an eye you can dip a toothpick in food color and then make a dot for the eye in the coating before it hardens on the ghost. You can also try the food coloring pens, though I don't think they would work as well.
If you have coating left over, or want to do a ghost with less prep, cut the bottom off of a nutter butter cookie and dip that in the white chocolate. Anything not used of the chocolate can be allowed to harden for re-use later or you can mix other things into it. Crushed peppermint candies are awesome mixed into the coating and dropped onto pretzels. Both cheerios and rice krispie cereal are also good mixed into the chocolate.
Whatever you do, use very low heat when you are working with the coating. If it is too hot for your fingers it will burn the chocolate. If you use the microwave use a low power setting (about 30% power is what I use).