I need some help for XPATH query to change the setting name "SettingName"

<configuration
<applicationSettings>
<MyApp>
<setting name="SettingName" serializeAs="String">
<value>valuetobechanged</value>
</setting>
</MyApp>
</applicationSettings>
</configuration

Can somebody help me with Xpath Query to change the value of SettingName?

Thank you...