You probably assigned a texture to it that looked like a plant. Hypershade is the main place you do all texturing in, but you can assign materials to objects by right-clicking>materials>assign new material then click the checkered box to the right of the color slider to choose a texture. The texture you used was probably that of a plant image. (use a file texture) As for the skin, you are talking about a skin shader. It's not much different from what I just explained, only your texture will look like skin instead of a plant.

If you want to change the color or texture of an object, you have to modify it's material. By default, Maya assigns the default lambert material to any object you create. If you want to give the object some color, you have to assign a new material to the object. (it's generally bad to change the default lambert texture) So, in hypershade you can create any material, texture, or shader-modifying node quickly. You can then select your object, right-click the material in hypershade, and choose "assign material to selection." This, obviously sticks the material in hypershade onto the object you selected.

So, this is basically how materials and textures work. Hope this helps.