To add a new topic page and list it in the "Collaboration Political Platform" page with the other topics, go to the "Collaboration" page and:
Click "edit" at the top of the page. (It's better to click the "edit" at the very top of the page than the "[edit]" along the side at the section you want to add to.) Add your new topic to the others listed, following the same formatting (note that the title is typed in twice, etc.). Then save the new page, clicking the "Save page" button.
The new topic and page is now created.
However, if you can't bring back up the "Collaboration Political Platform" page showing the listed topics, you might have to do the following: Go to one of the other topic pages, by clicking on one of them in the Main Page. Then go to the address bar at the top of the page and change the address to that of the new page you created. Do this by leaving the address as is except the very end where you delete the old topic and replace it with your new topic. Then click on that address to get to your new topic page. Type something in the space and save it. Then you should be able to bring back up the "Collaboration Political Platform" page and see your new topic listed there.