find & replace with user input

Trying to create a script/executable to replace "abc" text string in "myfile.htm" with input from a pop-up field. For example, launch this thing and a prompt is popped up asking the user to input what "abc" should be replaced with, then it inserts what the user inputs in place of abc in the myfile.htm.
"abc" will always be there...ie the string being replaced is static. Eventually, it will then ftp myfile.htm to a server, but I'll tackle that next (one thing at a time). This will ultimately be getting run from a windows xp box, but I figured it would be easier to figure out how to do this in bash (hopefully awk?), and try to make it work on xp from there.

myfile.htm:

may be vb script is a good option if you are implementing this with windows xp

An option would be to use JavaScript in your HTML file to change those instances. That would remove any OS dependency, and any changes would be client-only (not written to the server).

I was looking for an actual script, but perhaps this is not the place. Thanks for the info though, I will search out forums dedicated to VBS.