Ok, I tried texturing my cylinder object below using the 3D paint tool. I clicked on the "Assign/Edit Texture" button to give it a texture file and clicked accept...but then this happened. (Note that the circle balls revolving around the cylinder are child nodes to the cylinder, so the cylinder is parent) I don't know if this could be the problem.

so what does that transparent thing on my cylinder mean? and how can I get it back to it's original mode?

Thanks