If you don't have pastry bags, you can use a ziplock bag. Actually get two bags because there's a neat trick you can do.
Fill up one ziplock bag with the icing you'll be using. Cut the corner off at an angle. Cut enough off to let the frosting flow, but not too much. Now, cut an off the other ziplock bag in the same way but cut off half as much. Drop your star tip (that's the tip used for character cakes..like the cake you're describing) in to the cut corner of the unfilled bag. Drop the frosting filled bag into that and presto! The cool thing about doing it this way is if you have several different colors and only one star tip, it's much easier to change colors. Otherwise it's a huge mess..trust me.
I know, clear as mud. But let me know if you have questions.