The preferred way to install this extension is through composer.
Either run
php composer.phar require --prefer-dist insolita/yii2-metismenu "*"
or add
"insolita/yii2-metismenu": "*"
to the require section of your composer.json file.
Once the extension is installed, simply use it in your code by :
<?= \insolita\metismenu\AutoloadExample::widget(); ?>```