application with embedded sql ce 3.5 and sql server express data synch

Question

Hello everyone!
I would like to make a program with embedded database, and make it run on 5 computers.On the 6-th machine i would have sql express 2008, as a main server.
I want all the sql ce databases getting the datas from express db, when they go on a particular web site.The tables and columns etc are the same on each server /ce and express/.
So when the user logging in on the web site, gets the data from sql express automaticly, but can't change any of the data backward.
I've never made something like this...
Could anyone pls explain the methode and point me to right directions?/ie the logic it works and usefull web sites etc/
Thanks in advance