Gaussian is a program for computational chemistry. GaussView is the graphical viewer that assists with using Gaussian. Gaussian can be used for a variety of calculations, including molecular orbitals, energies, vibrational frequencies, and structure. Most of these explanations will be about how to use GaussView (to later use Gaussian).

The top bar has the typical options of File, Edit, Tools, Builder, View, Calculate, Results, Windows, and Help. There are icons on the next three lines. In the builder fragment window is a Carbon Tetrahedral with the carbon selected.
The GaussView 6.0 window.
Mouse Button Action Use
Left Click Selects or adds item
  Move left/right Rotate y-axis
  Move up/down Rotate x-axis
Scroll Roll Zoom in/out molecule
Right Move left/right Rotate z-axis
  Move up/down Zoom in/out molecule

Builder

The builder has a lot of buttons that each perform a different function. These functions, spaced like the builder, are:

Element Fragment | Custom Fragment
Ring fragment | R-group fragment | Biological fragment
Fragment Choice
Distance | Angle | Dihedral
Inquire | Add hydrogen | Delete group
Rotate | Click Atoms | Box-select | Drag-select
New build window | Center window | Rebond
Clean structure | Symmetrize | Builder Help
Deselect all atoms | Select all atoms

There are a number of icons. The top row has a periodic table and a book. The next row has a hexagon, an R group, and a helix. The next line is a methane fragment. The fourth line has a bond length button, an angle button, and a dihedral button. The fifth line has a question mark, a hydrogen, and a red X. The sixth line has a rotation, click, box-select, and drag-select. Line seven has a new page, shrink, and rebond. The eighth line has a paintbrush, plane, and questionmark. The final line has an arrow with grayed circles and an arrow with yellow circles.
The GaussView builder.