saving file

[shotjase]

Hey guys i have a header file for class:bitmap
i have a function in there called... void save (string filename) const;
i now hav 2 write a cpp file and write the function out. I have to save the bitmap into a file with the given filename 'string filename' that i have in my main.cpp

this is the function that needs to be completed

void bitmap::save (string filename)
{
// post : the image has been saved in filename

}

can any one help me plz i dont have much experience with c++