Graphic File Architecture

I've found it before, but have searched and searched and can't find it anymore I need to find a document with the architecture of a .ico file I'd like a site with alot of files, but right now I need .ico so I can read/write .ico files by opening them and parsing them/parsing an image and writing it to a file

...it may seem dumb that I'm not just using loadpicture, but I need to be able to load the file by hand for what I'm doing

so if anyone knows where I can find the file information of a .ico file please reply...

Thank you (in advance)