By working your way down the navigation tree structure, make sure the land object you wish to open is visible in the navigation tree (see image below).
Place your cursor on the land object you wish to open (see the first image below). When you do so, you will get access to an icon called "Open" (see the second image below).
Click "Open" (see the first image below). When you do so, the land object you are working with will open. When a land object opens, so does its object card (see the second image below). Via the land card you can work with a land object. For more information on how to do so, see section 10.3- 10.11. in the manual for Buildings. You will find it here.
