More Detailed Find and Replace

Hello all, my name is Yury and i do some light coding here and there when i have large tasks and want to finish them quicker!
I tried searching through the site and google for many many Find and replace scripts in both VB and Javascript, but the ones i found werent really savvy to what i was looking for.

Basically This is what im looking for, and if ANYONE could provide ANY help i would greatly appreciate it. At least point me in the right direction to start.

Im looking to write a general find and replace script, and here is what i want it to do...

I have top100.xls which is a spreadsheet with the top 100 cities in California sorted by population.

I have an html File where I have "Los Angeles" as the header, lets call it variable X.

What im looking to do is have this script is take every city (1-100) in the list, replace variable X with that city name, and save (output/write) it as X.htm

Again, any help appreciated

bump?

Javascript cannot read from or write to a file. You need to do this server-side using PHP.

i dont want this to be server side.
i need this program to run from this computer, and output to this computer