Customer Portal Website

Hi

I need to create a website with the functionality for my clients to be able to login. The clients each are on a different level and depending on the level you would be able to see certain files. Each customer must also be able to see his own customer documents.
Like a “customer portal” type of thing.

I would also want to be able to communicate with my customers through my web site i.e. send out communication via my website.

Any suggestions on a theme which could perhaps have such functionality? ??

thank you