Here is the marshmellow fondant recipe I used for my first cake. It worked out really well and was pretty easy to make.
1 bag of white marshmallows (8 oz)
Water (2 tbsp)
Icing sugar (1 to 2 pounds)
Note: grease everything (especially hands) with crisco or else the marshmellow with stick!
Put the marshmallows in a microwavable bowl, that has been pre-greased with crisco, and add the water. Put the bowl in the microwave and heat it for approximately 2 minutes until the marshmallows puff up.
Stir the marshmallows until they get smooth.
Add your icing sugar(little bit at a time). Stir using a greased spoon. Keep adding icing sugar until it looks like a dough. Turn out the “dough” on a greased work board and with your hands greased with Crisco start kneading the marshmallow fondant. Keep adding a little icing sugar at a time until it is not sticky anymore. It is ready when it feels pliable and ready to roll. Wrap unused fondant in cling wrap after greasing it up. Warm up hard fondant in the microwave for a few seconds at a time. If it's too dry add more crisco, if its too soft add more icing.