Those links are to parts of the documentation that Apple provides for the Cocoa API. Learning to navigate the documentation (and there is a lot of it) is important, since it describes what all of the classes and methods are. Unfortunately for regular AppleScripters, almost all of the documentation is for Objective-C (Apple's language of choice), but it can be converted to AppleScriptObjC fairly easily - see the release notes.
You don't really provide much information, but to speak a popup button's selection (the UI will be blocked while speaking) it would be something like:
onbuttonClick_(sender)
setgoodBadtosender's titleOfSelectedItem() astext
saygoodBad
endbuttonClick_
NSTextField is the class for a text field, and it inherits several common methods from the NSControl class - one of which is setStringValue, so to clear a text field you would add a statement in your button handler something like:
myTextField's setStringValue_("")