MX Simulator

I'm working on a kx125 skin and I'm wondering how do i put it in game i saved it as a png (kx125 shoie) and added it in game and didn't show up which i was expecting but what else do i need to do to add the skin in game

if i missed a thread that has this info please pull me up and a link would be awesome

thanks: Andrew

***UPDATE***

Ok i figured it out but i wanted to add my skin to this model http://puremxs.com/Bikes/BikeViewer.aspx?BikeID=600

he gave the template with the model but how do i attach it like what do i name it as or do i have to ask him if i can make a skin?

i have the name currently named to kx125-shoei but it comes up with the stock model and not the model in the link

can anyone help please