Scrolling down is the same as scrolling left or right, just take your camera's y position component and do the math on the Y drawn tiles.
psuedo code:
int start_tiles_x = Math.Clamp((int)(Camera.X / 32), 0, Map_width);
int end_tiles_x = Math.Clamp(start_tiles_x + 36, 0, Map_width);
int start_tiles_y = Math.Clamp((int)(Camera.Y / 32), 0, Map_Height);
int end_tiles_y = Math.Clamp(start_tiles_y + 36, 0, Map_Height);
Vector2 draw_pos;
For (int X = start_tiles_x; X < end_tiles_x; ++X)
{
For (int Y = start_tiles_y; Y < end_tiles_y; ++Y)
{
//position, sprite to draw
draw_pos = new Vector2(Camera.X % 32 , Camera.Y % 32);
int tileSprite_to_draw = ((X % 5) * Y);
LevelObject.DrawCall( draw_pos, tileSprite_to_draw );
}
}