Ok,

first question you need to ask yourself, are you going to code this yourself?
Do you have the expertise? because if the question is no, then I would suggest downloading a pre-made cms (Content Management System), once installed, you can create your template around this, and then have a backend that you can log into, and then add items whenever you chose in the admin area.

What would you be adding to this website? because that could be a factor in which CMS you could use. But here is a list of all the best CMS out there, one could be right for you.

http://www.opensourcecms.com/

The above link lets you test out many CMS so going on that and give it a try, to see if any of them are the way forward

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