Selection commands appear on the quad menu, on the main toolbar, on the Edit menu, and on the status bar.
By default, important selection commands appear on the main toolbar.
The Edit menu contains selection commands that operate globally on your objects.
The Selection Lock Toggle is located on the status bar. Locking a selection is useful when you are doing a lot of editing on a selection, and don't want to select something else by mistake.
The simplest method of selection is to turn on Select Object mode, and then click an object in a viewport (or drag to surround the object). While the method is simple, it is not effective for selecting multiple objects, especially in a crowded scene. Other tools let you select objects by name, filter out the kinds of objects you want to select, and to create named selection sets you can select repeatedly.