Social Networking - Entity Relationship Diagram

This is the entity relationship database that I have designed (so far) I managed to work out roughly where my entities would match, here's how I picture it:

> One university has many courses
> One course has many students
> One to many users can only be a single user.
> One to many companies can also be a single user.
> A user can have one to many posts
> And a single post can be on one to many blogs.

As you can see this is how I think it works out but it could be very different, I'll have a talk with Simon in either a surgery or my next seminar to get his opinion on my diagram.
I still need to add fields to each entity including the primary and foreign keys but I feel that this will not be too difficult to input.