Topics are simple mostly text pages of your help file. You may use topics either for writing some explanatory text that covers some aspects of your software or, for instance, to write a short introduction for a relatively large section of your help file.
You may rename the page right in the tree by clicking it or in the Title field of the properties pane.
You may also rearrange pages by dragging and moving them across the project tree. Use Ctrl+Up and Ctrl+Down keyboard shortcuts to change the order of sibling pages within a section.
You may also exclude (hide) a node from the output by selecting the node and pressing Delete key.