Create XML file from submitted form data (Was: desperately seeking help)

Hi friends,
i am in desperate need of your help in developing an application. the details are as follows:
using HTML/JS a form has been created, now i need to use either servlets or JSP to generate a XML file. this XML file should contain the the choices made by the user in the form of tags and it should be a dynamic one ie for every user selection made on the form, this XML should also automatically change.
i have absolutely no idea on how to proceed. i have gone through some tutorials but of no avail. i don't require u to develop the full code but atleast i need some code to start with.
i am in desperate need of ur help and am breaking my head for the last couple of weeks but i have not been able to even make a start. i require ur assistance. atleast if u can give me an idea with some sample code which will of great help to me.
i compulsorily need to use only servlets or JSP to generate XML.
thanks in advance and desperately waiting for a reply from you.