how to synchronize database in .net

i developed one windows application in c#.net. and one webapplication in asp.net(c#.net). web application is admin. windows application will be given to each user. there is one synchronize button in windows application. when user clicks that button he connects to the web application.
when he connects to the web application his database should be updated bases on web server databse. this is my requirement

how to do this.

i hope i will find solution for this.