Design an App Mockup

PLEASE NOTE THIS IS A DESKTOP APP NOT A WEB APP!!!! I need someone that can mock up a look for a piece of software that I would like to have built. It is a backup application that will allow our clients to backup to our servers. It will be mainly blue colors as it is considered cloud backup. I have a small idea of how I would like it to look like but I need someone to help me visualize it. At first I will need a windows version designed then after everything is up and running with that we will start focusing on mac. After that different platforms will be designed. If you have any questions please ask.