How to show popup when update version is available on server.? Is it solved by making service that run on background?

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C#

I created one application which is mainly complete but i have one problem that i want to create one service that run on background in which I want to show update popup when my application got update version from server....I am confused that I want to create window service or web service or WCF service for my application...or If you have another one idea to show popup then please guide its very urgent.. I think you can understand my question.

and Thanks in Advance..

What I have tried:

I directly create update form in my application but it will show only when I execute my application...but i want update popup even my application is exit.

#region VersionCheck
public void VersionCheck()
{
try
{
using (var client = new WebClient())
using (var stream = client.OpenRead("http://www.google.com"))
{
var versionInfo = FileVersionInfo.GetVersionInfo(Application.ExecutablePath);
string version = versionInfo.ProductVersion;
string query = "SELECT Version FROM Version_Info WHERE Id = (SELECT MAX(Id) FROM Version_Info)";
dr = con._Executereader(query);
if (dr.Read())
{
if (version != dr[0].ToString())
{
Update upform = new Update();
upform.Show();

}
else
{

}

}
}
}
catch
{ }
}
#endregion