To select the face on a smesh, hold down the Shift key and click in the white space of that face, being careful to avoid edges and nodes. Sometime there may be multiple faces at a position, stacked one behind the other, however only the closest face will be selected. The selected face will be highlighted. You can select as many faces as you want while holding the Shift key, and you can deselect in the same manner. There is no way to select multiple faces with a fence, only direct selection is available. When you select a face all of the edges and nodes associated with that face will become selected.
Selecting the Ignore Back facing option will limit the selection face, nodes, and edges to those on the side of the object facing the user.