I have a shape, I can't convert it to node. When I use the I don't see the mode, I only see this http://imagebin.org/131969

Thanks

Those tiny gray diamond shapes ARE the nodes.
I can't quite tell what you've got going on there....it looks like maybe a pattern...?? The tiny X, square and circle look like pattern handles, but it's hard to tell.

But you definitely have a path with nodes. No shape. To select a node, position the node pointer over the node. The node will turn red when you're in the right place. Then click. The node will turn blue (if it's a white background) when it's selected.