A topic can appear as a rectangle in the 2D Map or cone/pyramid in the 3D 'Scape, an item in the Hit or History Lists (see Search results -- the Hit List), a Pending Tray item (see Pending Tray - holding area for topics and occurrences) or items in the Navigation map in the Topic Center.
When topics appear they can, with very few exceptions, be treated in the same way -- drag and drop, make associations, delete them, search from that point down its branch and so on all described later.
When you are viewing the Map or 'Scape and a topic is selected, pressing the Tab key selects the 'next' topic, cycling through the topics on the level of the one originally selected. Shift+Tab, moves in the reverse direction.
Topic cones and pyramids can be made to float off the ground. Many users find that this makes the structure clearer, but some prefer to think of them as mountains, and firmly seated. Please refer to the paragraph headed Float the topic cones and pyramids in the section on customizing the 2D Wall adjustments. You cannot make rectangles float above the Map.