如何将地图纹理化到曲面上？

I'm attempting to create a 3d game using OpenGL. I have a very basic world and am now working on a character. I want to map a texture to the head which will be oval shaped. How do I do the mapping? I know how to map to flat surface. I'm wondering if the normals can be used to help but I've never done this before and when I search Google I don't have any luck.I'm attempting to create a 3d game using OpenGL