HTML5

I want to code a poker game in HTML5.

Can anyone point me in the right direction of where I can learn how to do this? tutorial site?

Not possible. You'd also need a few other vital programming languages

Html5 alone? no lol. You will need to learn html, css, PHP, and javascript to make a NICE looking and functional poker site.

If you want game as poker you have to use php or some different language for backend.

A poker game of what sort? 2D? 3D? If 2d then its easy as cake. (A weird simile). You need a little knowledge in html javascript, you can create a server in nodejs in which you could connect to through the client by using a module called socket.io or websockets. IF you want any more information don't hesitate to pm.