Where did the main page in magento go?

Question

PHP

Hello!
I added a slider according to this instruction https://magenticians.com/customize-homepage-magent...
After refreshing the page, I got an error, the report says:
a:4:{i:0;s:56:"Class SY\Slider\ Observer\Inserts\Homepage does not exist";i:1;s:11611:"#0 /home/q/qualit21/project-promo.ru/public_html/vendor/magento/framework..: ReflectionClass->__construct(' SY\\Slider\\Obser...')
Now this line 19 has the following entry:
$class = new \ReflectionClass($className);
Please tell me what to write where?
Thank you!

Answer 1

Because right away you need to install this extension https://landofcoder.com/magento-2-image-slider.html