please help me in solving this error in hibernate

By: er.pri*** On: Tue Apr 14 16:53:12 IST 2015     0 0 0	0
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment). log4j:WARN Please initialize the log4j system properly. Exception in thread "main" org.hibernate.MappingException: invalid configuration at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1484) at org.hibernate.cfg.Configuration.configure(Configuration.java:1425) at com.hibernate.mypackage.StoreData.main(StoreData.java:14) Caused by: org.xml.sax.SAXParseException; lineNumber: 3; columnNumber: 25; Document is invalid: no grammar found. at org.apache.xerces.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source) at org.apache.xerces.util.ErrorHandlerWrapper.error(Unknown Source) at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source) at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source) at org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source) at org.apache.xerces.impl.XMLNSDocumentScannerImpl$NSContentDispatcher.scanRootElementHook(Unknown Source) at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source) at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source) at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source) at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source) at org.apache.xerces.parsers.XMLParser.parse(Unknown Source) at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source) at org.dom4j.io.SAXReader.read(SAXReader.java:465) at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1481) ... 2 more	0