Are there any simple examples for web 2.0 custom controls?

I’m having trouble understanding how to create a simple table or button (or any html object) from the web 2.0 sdk ?
I read the sdk docs but being used to 1.0 version of the SDK it was unclear how to create anything other than a js alert. I just want to create (for starters) a with an onclick event, no big deal.
I didn’t find much info on this forum.
Am I missing something ?
Any real/useful examples out there I can take a look at?

Thanks
Roman