You typically attach them at the ends of the rod. Then, depending upon how long the rod is, and thus the weight, you may need additional supports in between the ends - one in the middle, or sometimes two equally spaced between the ends. Hard to say as it depends upon the size of your window. And you are right, without a traverse rod you can't open/close past a bracket.

One thing you could do if you want to leave the brackets where they are would be get two more panels and place them inside the brackets so that you could close them and still have the panels on the outside of your current brackets making the window appear larger.

beeps is right you typically attach at the ends, but don't worry you won't see them (so they won't look funny) since the first "attachment" is placed outside the bracket towards the finial and the rest are placed inside. this way when you pull the curtains close they don't pull away from the end of the rod. i think a picture might make that clearer...

Thank you! I knew there was an "obvious" solution.