How to set default app

[bugger]

I have handcent and when i click on my message icon, it asked me what I wanted to set as a default. I don't believe i clicked anything and went about my business.
I read that if I set my handcent as my defualt, when I click my message icon, it will bring up handcent.

I tried uninstalling and reinstalling to get that box to pop up, but it won't. What do I need to do so that i can access my handcent through my message icon?

I appreciate your help.

 

[KlaymenDK]

If you have two apps to do the same thing, it will ask you which one to use ... until you select "Use by default for this action".

If you want to undo that setting (which is what I understand is what you want), you need to go into Settings->Applications->Manage applications, then select the app that you have set as default for the action, and click the Clear defaults button in the Launch by default section. This should clear all the default-action associations for that app, and you will again be prompted for which app to use for your actions.