In structured editing it is important to know where you are, i.e. you must be aware within which element in the XML/SGML hierarchy you are editing or inserting your mouse pointer. There are 2 principal ways of doing it explained below. Before you start playing with these options, make sure that you have either a Template or an example file opened. as explained above!
In the View Menu of the main Menu bar you can define whether and how to display element boundaries. If you have a small screen (17'' or smaller and especially if you work under Windoze) I suggest that you make visible elements:
Menu: View->Element Boundaries (as Tags)
This is mostly how I work (despite having a 21'' monitor), unless I do proof-reading and minor editing, in which case I turn this view off.
Open up the "Structure View" (click on the icon in the little bar to the right as explained above). This View will always show you where you are. Now if you want to insert an element in some place of hierarchy, just insert the cursor in front or after an element. In order to avoid scrolling you can also open/hide sub-trees by clicking on the +/- signs to the left of Element Names. The -/+ to right hides/displays Attributes. Note: under MS Win this window wants to stay in front and obscures the document window, no idea if this annoying behavior can be changed.