@kishore_hemmady
For writing an attribute, if that's what you mean:
QXmlStreamWriter w = // ...
QDomElement e = //...
//...
QDomAttr a = e.attributeNode("Name");
// ...
w.writeAttribute(e.name(), e.value());
But now you're asking about QXmlStreamWriter, which you weren't before. I don't know why you're mixing this with QDom. Normally, you read everything with QDom, maybe make some changes, and then write everything back with QDom. Take a look at e.g. http://www.informit.com/articles/article.aspx?p=1405553&seqNum=4:
Using QXmlStreamWriter to write XML is the easiest and safest approach, but if we already have the XML in a DOM tree, we can simply ask the tree to output the relevant XML by calling save() on the QDomDocument object.