What you are looking for is the Unity Scripting Reference : Unity - Scripting API:
Use the search box in the top-left corner.
For example, search transform , then click on the first result : Unity - Scripting API: Transform
All of the variables and functions associated with that command are there. Click on position, and the description is there.
Lets try another : rigidbody : Unity - Scripting API: Rigidbody
click on velocity, and the description and an example is shown.
Another very useful one is raycast , this time click on Physics.Raycast : Unity - Scripting API: Physics.Raycast
The Unity Scripting Reference is very handy for checking what should be included in a command, e.g. with the RayCast link :
static function Raycast (origin : Vector3, direction : Vector3, distance : float = Mathf.Infinity, layerMask : int = kDefaultRaycastLayers) : boolean
this is basically saying :
if ( Physics.Raycast( start position as Vector3, Direction as Vector3, Distance as Float, Layermask [click on layermask for more info] ) ) : Returns a boolean (true or false)
See how you go =]