When managing your inventory you will easily be able to navigate through the sites by locating them on the inventory tree and selecting one.
Once selected, "Current Site" Tab will display the chemicals present in that inventory site, allowing you to manage your inventory whether that is adding editing or removing chemicals.
Selecting the "Display all in sub Levels' will display the chemicals present in all the sub locations of the site selected. Double clicking the site will open a new tab and display the chemicals present in the location.