OpenGL Rubic's Cube side rotations

i'm trying to implement a Rubic's Cube in Android Studio using Java and OpenGL.

Rendering and rotating the whole cube works just fine but rotating just one side (9 cubelets) doesn't

As far as i know the glTranslatef(x,y,z) method simply multiplies the current matrix with the translation matrix which i can specifiy as x,y,z. I'm pretty sure that i can somehow use that and the glRotatef() method to rotate just one side, but i don't know how.

 @Override
    public void onDrawFrame(GL10 gl) {
        // Clear color and depth buffers using clear-value set earlier
        gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);



        //Front-Faces
        gl.glLoadIdentity();                // Reset the current matrix to the Identity matrix
        gl.glTranslatef(0.0f, 0.0f, z);   // Translate into the screen
        gl.glRotatef(angleX, 1.0f, 0.0f, 0.0f);
        gl.glRotatef(angleY, 0.0f, 1.0f, 0.0f);

        gl.glRotatef(angleCube, 0.0f, 0.0f, 1.0f); // Rotate
        cube.draw(gl);

        gl.glTranslatef(offSetPositive, 0.0f, 0.0f);  //Middle-Right
       cube.draw(gl);

        gl.glTranslatef(0.0f, offSetPositive, 0.0f); //Top-Right
      cube.draw(gl);

        gl.glTranslatef(offSetNegative, 0.0f, 0.0f); //Top-Middle
      cube.draw(gl);

        gl.glTranslatef(offSetNegative, 0.0f, 0.0f); //Top-Left
      cube.draw(gl);

        gl.glTranslatef(0.0f, offSetNegative, 0.0f); //Middle-Left
      cube.draw(gl);

        gl.glTranslatef(0.0f, offSetNegative, 0.0f); //Bottom-Left
       cube.draw(gl);

        gl.glTranslatef(offSetPositive, 0.0f, 0.0f); //Bottom-Middle
       cube.draw(gl);

        gl.glTranslatef(offSetPositive, 0.0f, 0.0f); //Bottom-Right
        cube.draw(gl);




        //Middle
        gl.glTranslatef(0.0f, 0.0f, -2.1f); //Bottom-Right-Middle
        cube.draw(gl);

        gl.glTranslatef(offSetNegative, 0.0f, 0.0f); //Bottom-Middle-Middle
        cube.draw(gl);

        gl.glTranslatef(offSetNegative, 0.0f, 0.0f); //Bottom-Left-Middle
        cube.draw(gl);

        gl.glTranslatef(0.0f, 2.1f, 0.0f); //Middle-Right-Middle
        cube.draw(gl);

        gl.glTranslatef(offSetPositive+offSetPositive, 0.0f, 0.0f); //Middle-Left-Middle
        cube.draw(gl);

        gl.glTranslatef(0.0f, 2.1f, 0.0f); //Top-Right-Middle
        cube.draw(gl);

        gl.glTranslatef(offSetNegative, 0.0f, 0.0f); //Top-Middle-Middle
        cube.draw(gl);

        gl.glTranslatef(offSetNegative, 0.0f, 0.0f); //Top-Left-Middle
        cube.draw(gl);



        // Update the rotational angle after each refresh
        angleX += speedX;  
        angleY += speedY;  

        // On ArrowDown-Key Rotate 90 degrees
        if((angleCube > -90.0f) && (rotate == true)) {
            angleCube += speedCube;
            System.out.println(angleCube +"  " +rotate);
        } else if((angleCube < 0.0f) && (rotate == false)) {
            angleCube -= speedCube;
            System.out.println(angleCube +"  " +rotate);

        }

    }
} 

    public void draw(GL10 gl) {
        gl.glFrontFace(GL10.GL_CCW);    // Front face in counter-clockwise orientation
        gl.glEnable(GL10.GL_CULL_FACE); // Enable cull face
        gl.glCullFace(GL10.GL_BACK);    // Cull the back face (don't display)

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);

        // Render all the faces
        for (int face = 0; face < numFaces; face++) {
            // Set the color for each of the faces
            gl.glColor4f(colors[face][0], colors[face][1], colors[face][2], colors[face][3]);
            // Draw the primitive from the vertex-array directly
            gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, face*4, 4);
        }
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glDisable(GL10.GL_CULL_FACE);
    }
}