Is there anything about WebSphere in particular about the question? If not, I'd suggest to read up about REST, the JAX-RS API, and its reference implementation Jersey. The WebServicesFaq has a number of links on these topics.
Actually the problem was how to develop REST webservice in RAD 7.5. Is there any prebuilt implementation of JAX-RS. I had searched but not able to find any sample example on RAD 7.5 for prepackaged REST implementation. Please help.