You could save it as a bool in your settings and you should check at load event of first form. Your settings file should have a setting that I called "FirstRun" do this with following steps:
- Right click your Project
- Click "Properties"
- Click "Settings" tabpage(probably on the left)
- Add setting like I did as seen in image above
Note: The Scope
can be changed to "Application", if that is your application's need, since you didn't mention in your question.
Your Settings file should look like image below:
public void Form1_Load(object sender, EventArgs e)
{
if((bool)Properties.Settings.Default["FirstRun"] == true)
{
//First application run
//Update setting
Properties.Settings.Default["FirstRun"] = false;
//Save setting
Properties.Settings.Default.Save();
//Create new instance of Dialog you want to show
FirstDialogForm fdf = new FirstDialogForm();
//Show the dialog
fdf.ShowDialog();
}
else
{
//Not first time of running application.
}
}
Note: wrote this from my phone, so I couldn't compile to test
Edit: Checked code and added image from desktop.