Blender

Blender is an open source multi platform 3d modeling program. http://www.blender.org

Mouse roller zooms in.

Lower left button (cross here): refers to which mode you are in:

Press down roller button to scroll menu.

Navigating in 3D

Inserting Objects

Left mouse gets the pointer to where new objects will be inserted.

Blender Interface

Manipulating Objects

To move an object:

Left click, move and release. This will start to move objects.

More operations, like select, duplicate:

Transform Window

Click n. You can snap things to grid.

Questions

Say you have parts on a screen. How do you align them?