Installing Magento 2 extension is an easy task .. you just need to extract your extension zip file and place the folder inside your Magento 2 app/code directory so that the structure should be like app/code/namespace/module-name
then you have to run some commands for registering your Magento 2 extension
open terminal inside your Magento 2 directory, parallel to the app directory
run these commands-
giving read write permission to your magento 2 directory
sudo chmod -R 777 /path of Magento 2 folder such as /opt/lampp/htdocs/Training/Magento_2.0
if you are using linux operating system then you have to run this command . for windows it is not necessary.
for registering your extension
/opt/lampp/bin/php bin/magento module:enable Namespace_Modulename/opt/lampp/bin/php bin/magento setup:upgradefor compiling your extension code
/opt/lampp/bin/php bin/magento setup:di:compile
now flush your cache , delete cache folder from your Magento 2 var directory.