Select
Use the Select tool 
to select items (model entities, drawing views, etc.) in
a document.
Click Select
and select an item in the graphics area.
Box Select
You can select components in assembly documents by dragging a selection
box with the pointer. Click in the graphics area and drag a box in any
direction.
When you select from left to right, all items
within the box are selected. When you select from right to left, items
crossing the box boundaries are also selected.