First things first - you need to have defined statements of what you want the site to do, and who it is aimed at
Then you might find there is a pre-built script available free from the open source world, that does what you need and just needs a few tweaks.
Without digging into your site (yuch factor 10 on the colours) I'm guessing you need an extensible CMS like Drupal or Joomla, so that you can add the exact plug-ins you need for the tasks you want the site to perform. However, they do have a steep learning curve if you've never used anything like them before.
If you're wanting "members" to be able to log-in and leave documents announcements etc, you definately need a CMS system based on php & SQL - anything else is not going to be able to handle the data management and user verification.
You could try working around things by using a forum system like SMF, which has thousands of "community" style plug-ins, or phpBB (very weak security), or pay for one of the higher end boards like InVision.
Like I said - first things first - have you defined the needed functions and purpose, and created a mission statement for the site yet? Without that, you might as well try to harvest a wheat field with nail clippers.
Gaz