OpenGL Squares and Arrows - c++

Question

i'm trying to create a square and on top of it i'm creating an arrow. its like a 2D meter something similar to that. But i don't know how to create the arrow on top of the square.
int count = 1;
for (float y = 1; y < 11; y++) {
y1 = y1 - 0.51;
y2 = y2 - 0.51;
float x2 = -2.0;
for (float x1 = -2.5; x1 < 2.5; x1 = x1 + 0.51) {
glColor3f(windy[count], 1.0, 0.0);
glVertex2f(x1, y1);
glVertex2f(x1, y2);
glVertex2f(x2, y2);
glVertex2f(x2, y1);
count = count + 1;
x2 = x2 + 0.51;
}
}
glutSwapBuffers();
glEnd(); //End the glBegin Function
And this is what i want to be on top of it.
glBegin(GL_LINE_LOOP);//start drawing a line loop
glVertex3f(-1.0f, 0.0f, 0.0f);//left of window
glVertex3f(0.0f, -1.0f, 0.0f);//bottom of window
glVertex3f(1.0f, 0.0f, 0.0f);//right of window
glVertex3f(0.0f, 1.0f, 0.0f);//top of window
glEnd();//end drawing of line loop

Answer 1

Why did you swap buffers before glEnd() call:
int count = 1;
for (float y = 1; y < 11; y++) {
y1 = y1 - 0.51;
y2 = y2 - 0.51;
float x2 = -2.0;
for (float x1 = -2.5; x1 < 2.5; x1 = x1 + 0.51) {
glColor3f(windy[count], 1.0, 0.0);
glVertex2f(x1, y1);
glVertex2f(x1, y2);
glVertex2f(x2, y2);
glVertex2f(x2, y1);
count = count + 1;
x2 = x2 + 0.51;
}
}
//glutSwapBuffers(); // wrong place
glEnd(); //End the glBegin Function
glutSwapBuffers(); // Must be after draw operation
to draw arrow on the top of the shape must be even more:
int count = 1;
for (float y = 1; y < 11; y++) {
y1 = y1 - 0.51;
y2 = y2 - 0.51;
float x2 = -2.0;
for (float x1 = -2.5; x1 < 2.5; x1 = x1 + 0.51) {
glColor3f(windy[count], 1.0, 0.0);
glVertex2f(x1, y1);
glVertex2f(x1, y2);
glVertex2f(x2, y2);
glVertex2f(x2, y1);
count = count + 1;
x2 = x2 + 0.51;
}
}
//glutSwapBuffers(); // wrong place
glEnd(); //End the glBegin Function
// draw arrow
glBegin(GL_LINE_LOOP);//start drawing a line loop
glVertex3f(-1.0f, 0.0f, 0.0f);//left of window
glVertex3f(0.0f, -1.0f, 0.0f);//bottom of window
glVertex3f(1.0f, 0.0f, 0.0f);//right of window
glVertex3f(0.0f, 1.0f, 0.0f);//top of window
glEnd();//end drawing of line loo
// atlast we can swap our buffers
glutSwapBuffers(); // Must be after draw operation