How to convart text file in xml file

in .net if have txt file you can save it as xml file with changing extension but take care of content of text file it must follow the xml structure as it will be saved with no problem but later on if u want to use xml file it will throw error if its not acc to xml format like proper closing of each and every tag , xml header , & sign in xml file must be taken care, it can be represented with & , like this