Please read the short documents in the "How-To Work With..." section below.
If you do not want to spend too much time on it, read the introduction and the articles about pages and folders. You may read all the others later whenever you feel the need to use one of the other content types.
By doing so you should be able to create your first documents/pages after 15-20 minutes, and to make almost full use of the system after 1 hour of learning. If even this seems to be too much time for you, there are (english) help-"bubbles" showing up on many items in this system once you keep your mouse over them.
And: This little amount of your time invested in learning the system will help you and your colleagues to save lots of time that you used to spend on rather more inefficient ways of communication ...