Has anyone done this ?
If so,please share your experience:)
Has anyone done this ?
If so,please share your experience:)
The first step would be to develop use cases. Lay out specifically how the application will be used and where points of interaction will be. Only afterwards should you focus on implementation.
I spent about twenty minutes starting to write an answer for this, but it felt like I was writing a lecture. I think it's impractical to expect an answer for something so divergent as designing a web-UI in a top down way. I mean, what you're asking for is basically this: "How do you guys do your job". It's so broad, and in-depth it's insane.
However, all that being said: It's great that you've asked this question. Conceptualisation and Early Design phases are some of the most interesting and creative roles you can get in Web-Development. What you really need to do is find a starting point. That probably means that you need to go out and learn requirements gathering, both Business and User Centred Design methods.
I'm not a proponent of Business Centred Design, but only because so many other people are. So, I'll focus on UCD. If you like books I'd recommend About Face 2.0 by Alan Cooper, which is a good foundation in Interaction Design. If you don't want to purchase a book, you could go to usability.gov and start to learn.
By using things like Contextual Interviews, Card Sorting, Contextual Enquiry and other UCD methods much of the interface will be designed naturally.