Design a Mobile Application Mockup on Photoshop or any other program

I would like to create a design for my mobile app so that I can send it to developers so that they can see what I want my app to look like, it's functions and how smooth I want it's transitions from each page to be to be. I am creating an app for sports recruiting for prospective college and professional athletes. It has to be simple but attractive and effective. Location settings, social network integration, Yellow, white and purple as the main colors. Easy to navigate. Separate sign up pages: Coaches, Students athletes, free agent professionals, school/organization. I will describe more to whomever I give the contract to.