How to add objects to buffer? opengl

In this program I want to draw polygons.

Firstly I made sth like that:

GLuint VertexArrayID;

example of drawing polygon:

if (figure == RECTANGLE)
{
    data[0][0] = px1;   data[0][1] = py1;
    data[1][0] = px2;   data[1][1] = py1;
    data[2][0] = px2;   data[2][1] = py2;
    data[3][0] = px1;   data[3][1] = py2;
    vertex_count = 4;
}
vbo_create(vertex_count);

And here is vbo crreating function

void vbo_create(int vertex_count)
{
    if (vertex_count > 0)
    {
        glGenBuffers(3, VertexArrayID);
        glBindBuffer(GL_ARRAY_BUFFER, VertexArrayID[0]);
        glBufferData(GL_ARRAY_BUFFER, 2 * sizeof(float), data, GL_STATIC_DRAW);
    //GLfloat* data = (GLfloat*)glMapBuffer(GL_ARRAY_BUFFER, GL_READ_WRITE);

        glVertexPointer(2, GL_FLOAT, 0, NULL);
        glEnableClientState(GL_VERTEX_ARRAY);
        glDrawArrays(GL_TRIANGLE_FAN, 0, vertex_count);
        glDisableClientState(GL_VERTEX_ARRAY);
    }
}

The point is that I want to save all created objects in one buffer, but I have no idea how to do it. I tried to make an array of VertexArrayID, but it doesn't worked correctly. Any suggestions?

Let's say, you have 10 triangles. Then, you would just put 30 vertices in this one buffer and render all of it with GL_TRIANGLES. You could also add four vertices and use GL_QUADS. It is a good idea to have rather few vertex buffers if that works for you.