It's hard to say as you have given very little information.
1. What skillsets do you have with regards software engineering and web application development (e.g. languages, frameworks etc.)?
2. What features does the application require? Anything special about them? You mentioned a registration system and allowing a user to view a page containing a variety of info. Where do you want this info to come from (e.g. XML documents, flat files, database system, external cache etc.) and how is it being displayed (e.g. client-side widgets, portlets, full page scripts etc.).
3. What is the budget for the project, deadline and how much functionality does it require? i.e. Do you need mostly premade scripts as you don't have an experienced developer on board or would you like to create a lot of custom features from scratch.
Lots to talk about.
If you do decide to go with a premade CMS (such as Joomla), be aware of the pros and cons in the long run.
“The best thing about a boolean is even if you are wrong, you are only off by a bit.”