One Entity

Left-click on the node you want to select. You will see the selection circle appear around it.

Multiple Entities

Drag a block with mouse around the entities you want to select– while keeping the left-click button in.

Once selected, the nodes will be highlighted as in the picture below.

Multiple Entities one at a time

When faced with multiple nodes but you only want to select specific nodes, use Shift + left-click. Shift + left-click on each node you want to select and they will be added to the selection.