I hear that there is some type of stake delegated proof of stake or some interest or yield
And how can i use that stake system
Delegated Proof Of Stake - DPOS is the consensus mechanism behind Bitshares.
It means that you can vote (delegate) with your BTS tokens (stake) on witnesses (block producers).
If a witness receives enough votes, she will receive a salary in exchange for her block producing services (through dilution).
There is no yield anymore on Smartcoins like there was during Bitshares 0.x but you can earn a profit with them like with any other financial asset, buy high/sell low or sell high/buy low.