How to draw Excel horizontal bar chart?

I have problem displaying horizontal bar chart in Excel, instead it displays a column chart. My code looks something like this:

DO(Wasp_Path_moveTo(path, x0, -(y0)));
DO(Wasp_Path_lineTo(path, x0 + dx, -(y0)));
DO(Wasp_Path_lineTo(path, x0 + dx, -(y0) + dy));
DO(Wasp_Path_lineTo(path, x0, -(y0) + dy));

Can anyone help on this, or give a rough skeleton on how to write the code for this in C?

Thanks.

Are you trying to do this in C or in Excel?

I m doing it in C.

Can you give a rough idea on how to implement it?

Thanks