In Notepad++ go to
Plugins > Plugin manager > Show Plugin Managerthen findXml Toolsplugin. Tick the box and clickInstall
Open XML document you want to validate and click Ctrl+Shift+Alt+M (Or use Menu if this is your preference
Plugins > XML Tools > Validate Now).
Following dialog will open:
Click on
.... Point to XSD file and I am pretty sure you'll be able to handle things from here.
Hope this saves you some time.
EDIT:
Plugin manager was not included in some versions of Notepad++ because many users didn't like commercials that it used to show. If you want to keep an older version, however still want plugin manager, you can get it on github, and install it by extracting the archive and copying contents to plugins and updates folder.
In version 7.7.1 plugin manager is back under a different guise... Plugin Admin so now you can simply update notepad++ and have it back.
