Transparency c++/opengl/sdl

Hi, Im working with sld and opengl but I cant figure out how can I make the background of an image transparent. I imported a gif library for sdl but it still does not work.

glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
glOrtho (0, XSize, YSize, 0, 0, 1);
glMatrixMode (GL_MODELVIEW);

glDisable(GL_DEPTH_TEST);
glEnable(GL_TEXTURE_2D);

SDL_PixelFormat RGBAFormat;
RGBAFormat.palette = 0; RGBAFormat.colorkey = 0; RGBAFormat.alpha = 0;
RGBAFormat.BitsPerPixel = 32; RGBAFormat.BytesPerPixel = 4;

#if SDL_BYTEORDER == SDL_BIG_ENDIAN
RGBAFormat.Rmask = 0xFF000000; RGBAFormat.Rshift = 0; RGBAFormat.Rloss = 0;
RGBAFormat.Gmask = 0x00FF0000; RGBAFormat.Gshift = 8; RGBAFormat.Gloss = 0;
RGBAFormat.Bmask = 0x0000FF00; RGBAFormat.Bshift = 16; RGBAFormat.Bloss = 0;
RGBAFormat.Amask = 0x000000FF; RGBAFormat.Ashift = 24; RGBAFormat.Aloss = 0;
#else
RGBAFormat.Rmask = 0x000000FF; RGBAFormat.Rshift = 24; RGBAFormat.Rloss = 0;
RGBAFormat.Gmask = 0x0000FF00; RGBAFormat.Gshift = 16; RGBAFormat.Gloss = 0;
RGBAFormat.Bmask = 0x00FF0000; RGBAFormat.Bshift = 8; RGBAFormat.Bloss = 0;
RGBAFormat.Amask = 0xFF000000; RGBAFormat.Ashift = 0; RGBAFormat.Aloss = 0;
#endif


SDL_Surface * orig = NULL;

orig = SDL_LoadBMP("image.bmp");
if(orig == NULL){
....
...

Does anyone know what may be the problem?

PS I also tried png. Could anyone help me with that please? Ive been trying to figure it out for over 5 hours

First, please use code tags next time you post.

Did you set the OpenGL blend mode to one that supports a alpha blending? Usually you'll want something like:

Thanks for you rreply but i just now found what was wrong.

glDisable(GL_DEPTH_TEST);
glDisable(GL_BLEND);

draw non transparent textures
...
..



glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA ) ;

glEnable( GL_BLEND ) ;
glBlendFunc(GL_DST_COLOR,GL_ZERO); // <-- this is the key to transparency !!!!!!!

draw trasnparent textures
..
..