Thanks Leonid.

That was very helpful, but I still have the same question.

All I see is 'Post To Feed' in a space.

If "spaces can be used to hold any sort of content," how do I start a discussion, add an article, or upload a file to the SPACE?

There is no clear way to do it. I've clicked everywhere in the space I've created. All I see is "empty" with no button to click for new discussions, posts, file....

TY.