i want to create forum using yii 2.0 same like http://www.yiiframework.com/forum/

actually i have to create forum app in Yii2.0 similar to http://www.yiiframework.com/forum

if i can get any how source code with database design it would be great for me to understand

You can ionstall any popular open source forum and see database design. Also github have a lot of repositories with forum’s engine