Match root element

/My/Element 

Match sub element to current node

./Sub/Element 

Match nth element

 /My/*[n] 

Match nth Some element

/My/Some[n] 

Match any text value

/My/*[text() ='value'] 

Match the text in Some element

/My/Some[text() = 'value'] 

Match any attribute

/My/*[@att = 'value'] 

Match the attribute in Some element

/My/Some[@att = 'value']