UXPin makes an online wireframing and documenting tool for UX design work. I don't know much about their tool as I've never used it. It might be worth investigating. Anyway, they also publish reports/eBooks about UX and IxD topics. I have direct links three of them below and there are more you can find on their site here (scroll to the bottom of the page). I think these books will be quite useful as you begin prototyping/designing. FYI - When they use "mockup" they are talking about high-fidelity prototypes.