sed/awk are really about regular expressions.
check this answer on stackoverflow why parsing HTML/XML with regular expressions is a bad idea.
for XML you really need to build a DOM of the document and then find your information. there are cmdline tools like xmlstar that allow you to get information out of XML-documents.
but don't try using sed/awk.
PS: of course, you might be able to create a simple regular expression that can extract the information needed on the files you happen to encounter in real life. e.g. the following will print the 5th line of the document, which (in your example) holds the relevant information.
sed '5!d' MyXML.xml
but this makes an assumption about the layout of the file, which has nothing to do with XML.