Please understand that this is just experimentation for the heck of it.
Although it is not really a programming question, I would like to know how windows interprets .exe files. I want to know how I can extract instructions from executable X and add them to executable Y (perhaps a pointer in the exe?). So the result would be executable XY, which would first execute instructions from X and then carry on with Y (basically infecting Y with X without making Y disfunctional).
Thanks for the help!