glTranslatef and coordinate system

+y
              |
              |
              | __ __ __ +x
             /
           /
         /
       +z

please , i want to know if the coordinate system we are working on
opengl in organized in the above way
because when i do:
glTranslatef( 0.0,0.0,-5.0);
the object move in the +z instead of getting backward , why?!!!!!!!!
here is the full code

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

glTranslatef(0.0,0.0,-5.0);
glColor3f(0.0,1.0,0.0);   //green
glutSolidCube(1.0f);      //cube 1

glLoadIdentity();
glColor3f(1.0,0.0,0.0);   //Red
glutSolidCube(2.0f);     //cube 2
---
u will find that the first drawn cube will get forward to camera
instead of moving backward along the -z axis