What language are you using? The general concept would be to upload your application update to the internet, have a separate program that reads the URL of the application update, compares in the the current application, and replaces the current application if necessary.
Since I don't know what language you are using, I'll put an example in pseudocode.
//Updater program concept
NewProgram = ReadFromURL("www.mysite.com/MyProgram.exe")
OldProgram = LoadFile("C:\MyProgram.exe")
if NewProgram != OldProgram then
WriteFile("C:\MyProgram.exe", NewProgram)
RunFile("C:\MyProgram.exe")
Sorry if this is a bad example, but this what the best I could do with limited knowledge