I install magento2 in my system and its work properly but when i changed in less files then it's not affect in frontend.
then how can i compile
less files in magento2 for get css effect in frontend.
This page in the Magento 2 documentation pretty well covers using Grunt to compile less. http://devdocs.magento.com/guides/v2.0/frontend-dev-guide/css-topics/css_debug.html