Choose either Drag or Click mode. The mode of selection will displayed in orange, to change the mode - simply click on the button and it will change. You can flip between these modes even in the middle of a selection if you need to select an item in a different way. You are NOT requried to stay in the one mode whilst making selections.
Click on the hiearchy level buttons required for your selection. For example Network + Station Group, selected buttons will have an orange background. The highest level in the hierachy that has been selected will open a selection window in this instance it will be the network level. Users can then double click on a netwok such as Network 9 etc to breakout the stations that make up that network.
Make your selection by either clicking on the checkbox next to the item if you are in the Click Mode or drag items into the selected box if you are in Drag Mode.