When your program is loaded by the client (in say its browser) you can work with HTML, various scripts, applets and stuff like flash movies, but none of these can directly affect files (there are alternatives to the previous like ActiveX, but I doubt if that's what you want)
If you want the user to be able to submit files, do something like
That will allow your server to recieve files from a client computer.....You just need to decode it and do whatever...
<FORM ACTION="http://MyDomain.com/MyCGIProg" ENCTYPE="multipart/form-data">
Upload your ASM file
<INPUT TYPE="file" NAME="Upload_Name">