Virtual Hard Disk or VHD acts like a normal hard drive built into your computer. Cool thing is, it comes in a form of a single file so you can make a copy of it and virtually attach it to any other Windows computer.
Dropbox is an amazing cloud based web service enabling you to store your stuff like pictures and documents and access them from any device with an Internet connection. Plus you can share the stored items with others.
Image overlay pattern comes in very handy when a website has a full screen image or a video as a background. Applying a pattern can make things more readable and easier on eyes. Let's Photoshop.
You just bought Nexus 4 and you don't know anything about Android operating system, so I will guide you through literally first steps on this great phone.