Create an intranet on existing website

I’d like to be able to create a staff area which is totally secure, i.e. a login to access it. I also want to protect staff confidentiality – i.e. where staff members with their logins cannot view any other ‘members’ accessing the area. Security is key here.

I want this to my on my existing website if possible – I don’t want to create a new website or it to mess with my existing website (see above URL).

It just needs to be quite simple. I want to share some documents with all members and also perhaps restrict access to some documents – if possible, although not essential.

It would also be great to have a little newsfeed style thing where I can post little messages about holidays, news, updates on work, company ethos stuff, etc.

Does this make sense?! It would be great to be able to do this in as simple a way as poss. I am not a developer so remember this!, but am not scared to have a go at stuff myself.

The page I need help with: [log in to see the link]