getNumMaterials() getVertex() questions

i want to animate some of my textures but i dont exactly know what some of these commands actually mean:
mesh.getVertexArrayLength() : this always returns -1
mesh.getNumMaterials() : what Materials?
mesh.getVertex(a,b) : how do i know which vertex im selecting with this command
vertex.getRGBA() : returns crazy negative value

-mesh.getVertexArrayLength() needs a const 0 or 1(quads or triangs)
and gives vertices number.
-mesh.getNumMaterials() are the materials selected with in F5 window
-mesh.getVertex(a,b) you can find it only trying(for complex meshes)
-vertex.getRGBA() gives a negative number with -1 for white and -16777216 for black