how to set appropriate color

hi everybody
Im just newbie in opengl and I face difficulties to set the
appropriate color for my drawen objects using this code:
////////////////////////////////////////////////////
glPushMatrix();
dif[0]=0.5; dif[1]=0.4; dif[2]=0.1; dif[3]=0;
spc[0]=0.0; spc[1]=0; spc[2]=0.0; spc[3]=0.0;
glMaterialfv(GL_FRONT,GL_SHININESS,dif);
glMaterialfv(GL_FRONT,GL_SPECULAR,spc);
glTranslatef(0,0.49,-2.8);
glScalef(3,1.82,0.01);
glutSolidCube(2.2);
glPopMatrix();
//////////////////////////////////////////////////////////

I only get small range of colors by changing dif parameter. However i
change dif i get yellow, blue, green or red only. But if i change the
color of sphere i get wider range of colors. For example i want brown
or light blue colors how can i set them.
.