The remaining four orbital elements orient the orbit with respect to the Earth.
The plane of the orbital ellipse is oriented by two angles: the inclination and the right ascension of the ascending node.
Inclination describes the orbital plane's tilt angle with respect to the equator.
Inclination also specifies the highest latitudes (North and South) over which the satellite directly overflies. A zero inclination describes an equatorial orbit; a 90 degree inclination describes a polar orbit. Inclinations greater than 90 degrees describe orbits that move against Earth rotation (called retrograde).
An orbit's ascending node is its SouthtoNorth equatorial crossing.
The right ascension of the ascending node is the angle measured eastward from the Vernal Equinox to the ascending node. The Vernal Equinox is the Sun's apparent ascending node (marking the beginning of the Northern hemisphere's spring.
Argument of perigee is the angle measured in the direction of satellite motion from the ascending node to perigee.
True anomaly is the angle measured in the direction of motion from perigee to the satellite's position at some defined epoch time. Mean anomaly describes what the satellite's true anomaly would be if it were in a circular orbit. You can compute mean anomaly from the orbit's true anomaly and eccentricity. The commonly available Keplerian elements use mean anomaly.
The Celestial and Orbital Mechanics Web Site is a good reference for orbital mathematics and related software, including source code.
