when i add an image in the xna project , the photo appears with its white background how can i make the photo appears without its background (make it transparent )

You could set the colour key property to white in the content processor properties for that image and set colour key enabled to true.

I haven't tried this myself so their might be another step in the code to actually get it working.

Else you could set the alpha in an art package like photoshop then call spriteBatch.Begin(SpriteBlendMode.AlphaBlend).

HTH.