Slider help

[dude77]

Hi, I'm new at skin making. I've made my design, chopped it into .png images, added them in the materials etc. etc. I guess I can say I'm pretty done with it. The problem is I just can't create a time slider and a volume slider. I can't seem to understand what images are needed and what properties I need to set. Considering I have an Image of the actual slider button and an image of the bar on which it needs to slide, can someone explain to me step by step, what must I do?