Wittgenstein's picture theory of meaning

All I ever hear about the TLP is the picture theory of meaning. But then I read something like this: http://philosophyktl.blogspot.com/2010/01/what-wittgensteins-picture-theory-is.html
And all I can do is appear confused.

3 The logical picture of the facts is the thought.

Is this the so-called 'picture theory of meaning'? Or do we need to add:

4 The thought is the significant proposition.

Is this when I am supposed to say, "Now I understand the picture theory!" because LW said some thought was significant?

I think we need prop 5 to make sense of what a proposition is. It is a truth-function. But significant ones are truth-functions of a logical picture of facts. Surely LW doesn't describe a picture. He gives a picture. Or am I mistaken?

And if he does give a picture, what is it? 5.101 or the very book numbered to 7, or something else? The general form of proposition, maybe?