Camera is not moving

As a newbie, i’m learning opengl. But i stuck…How to move camera + And why my cube is visible partial.

#include<GL/glut.h>
#include<stdlib.h>
#include<iostream>
using namespace std;

float angle = 0;
float lx = 0, lz = -1;
float x = 0, z;

void SpecialKey(int key, int x, int y)
{
	float fraction = 1;
	cout << key << endl;
	switch(key)
	{
	case GLUT_KEY_LEFT:
		z += 1;
		cout << z << endl;
		break;
	case GLUT_KEY_RIGHT:
	case GLUT_KEY_UP:
	case GLUT_KEY_DOWN:
	}
}

void Box(void)
{
	glColor3f(1, 1, 1);
	glBegin(GL_POLYGON);
	glVertex3f(0, 0, 0);
	glVertex3f(10, 0, 0);
	glVertex3f(10, 10, 0);
	glVertex3f(0, 10, 0);
	glEnd();
}

void Display(void)
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glMatrixMode(GL_MODELVIEW);
 `   glLoadIdentity();
	gluLookAt(5, 4, z,1, 1.0f, 1,0.0f, 1.0f, 0.0f);
	glPushMatrix();
	
	glPopMatrix();
	glutWireCube(10);
	glutSwapBuffers();
}

void init(void)
{
	glClearColor(0, 0, 0, 0);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glOrtho(-100, 100, -100, 100, 0, 10);
}

int main(int argc,char**argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutInitWindowPosition(100, 100);
	glutInitWindowSize(500, 500);
	glutCreateWindow("Practice");
	init();
	glutDisplayFunc(Display);
	glutSpecialFunc(SpecialKey);

        glEnable(GL_DEPTH_TEST);
	    glutMainLoop();
	    return 1;
}