XML files consist of tags like <objective> and the text. The relationship between various tags and text is defined in the DTD descriptor - a rather outdated way to enforce restrictions on the XML structure, it is currently being replaced by XML Schema, but is still broadly used. You do not need to understand the DTD syntactic or be able to write your own DTD to use them in this project, but DTD knowledge is very useful.
XML editors generally allow verification against DTD in the real time, so that you always create the data file in the correct format. If you do not have an access to the XML editor, the verification is more complicated. I recommend using Chami's HTML Kit http://www.chami.com/html-kit/ with XML Validator plugin http://www.chami.com/html-kit/plugins/info/hkxmlv/ . In order to enable DTD verification, you should uncomment two lines at the top of XML:
<!DOCTYPE resumes SYSTEM "resume.dtd">
<resumes xmlns="http://xmlresume.sourceforge.net/resume/0.0">
and comment out the root element in its simple form:
<!--resumes-->
The DTD descriptor should be placed next to the source xml file. Now let's talk about the various DTD involved.
Now you have your resume in the XML format, more or less satisfying to the DTD. You do not have to achieve the absolute acceptance of your structure, in most cases the transformation engine will tolerate (i.e. ignore) small problems without complaining. The transformation engine is NOT verifying your XML against DTD, it is simply trying its best.
If you have an access to your own webserver, it is rather convenient to keep your xml resume there, editing it either directly on the file system on via ftp/WebFolder(WebDav) access. Type the URL for your data file into the Source box on the main page and select the transformation style. Alternatively, you can upload the XML data directly to our server.