I have a rock music site. I want to display some poker text-ads in my web site. Is it ok for Google Adsense? Could you please help me?

Probably not. First, your site is not talking about Poker, and will not deliver irrelevant ads to your site. Second, poker ads is a kind of gambling information which is prohibited under Google TOS.

You can not choose what ads to show for your google. Google choses the ads base on the keywords it gathers from your texts.