want to create state combo box block in drupal

I want to list states in a combo box to be d开发者_如何学JAVAisplayed in block in left side bar. Depending on the selecting of state I want to filter the HTML code within page nodes.

How can I do it?

1. If you are unfamilliar with how Drupal modules are created, work through Creating modules - a tutorial: Drupal 6.x
2. Create a form. The Forms API QuickStart Guide and the Forms API Reference tell you how this is done in Drupal.
3. Put the form into a block by implementing hook_block.

How to proceed from there depends largely on what type of filtering you need. In any case hook_nodeapi is invoked on various node-related occasions, so you might want to implement it to do the actual filtering.