Snail forum is just another forum powered by yii2. You can use it as a yii2 application example for yii2 learning. The project is under head development now, don't use it in your production.
Edit the file `config/db.php` with real data.
Import snail_forum.sql into database.
Create a new vhost and make `web` as the web root dir.
Visit this url /requirements.php to check whether your environtments can run yii2. If you see any errors, just follow the instruction on the page.