Elements are located in the Structure Menu to the left of the screen.

Expand the sub-folder you are interested in. Depending on the element hierarchy level the folder names will be slightly different.
 
 
Left-click the element you are interested in to bring up the element details page on the right. If you make any changes, you need to press the Save Element button before moving to another element.
 
 
You can modify a structure's element hierarchy, including adding new elements and archiving unwanted ones by following the article:
Consistent Element Inventories 2 - Modification options and requesting a change