Click once on the top carbon atom Use the 'Select Connected' menu command from the Edit menu
As you will notice, all atoms directly connected to the selected atom are added to the selection. Alternatively, you can also make a selection by shift-clicking on the elements you want to select.
Click in empty space Click on the top carbon atom Shift-Click once (without moving) on each of the top hydrogen atoms
This has almost the same effect (in this case you have not selected the second carbon atom).
