2d game engine

I am learning C right now. I hope to make a game called War of The Ancients. I need a 2d (for now :-P) monster fighting engine. I would like to know how to creat one of these. This engine will have monsters set in different spots on the map. You will "run" into a monster and move into a different scene with the monster. I need to know how to make this happen! Once in the battle you will have to attack and kill the monster using the weapon your class uses. I dont know how to do this...I need to know what all my artist needs to draw also (i.e. frames or one picture or how do I make it move?!) Also I dont want to be like most RPG''s and have set looks for each type of char. I want them to be able to choose themselves and also make their own. How would I make an engine for choosing your look? I am fairly new to programming and assistance would be appreciated.