Web GUI design issue

[soham]

I am new to Web Page Designing.
I am using Struts2 framework for the same. There is a RESTFUL API implemented for the same which will perform all the tasks for client(web interface). I have to design the web interface which will contact the user-agent. Interface which I will be designing will be interacting with the API (user agent) and responses from the agent will be displayed to the client.In short API handles all the activities at the back end. I did not find any resource on the internet helping me how I could do this.
Links or references would also help me solve this problem and help me get started.

Thanks.