How to use sessions in windows form application

Thank you so much for your responses...

But i do not use login on my application. on page load I have a list box that has names and two (Clockin and Clockout) disabled buttons, if a person select their name that is when the buttons get enabled.

When the name is selected from the list box, the clock in button gets enabled; when a person clicks on that button they are able to clock in on the system and the button clock out gets enabled, then they are able to clock out of the system as well.

The only problem is when a person clocks in on the system and then decide to close the application, next time they open the application, select their name from the list box the clock out button must be enabled for them to clock out. The system must not allow them to clock in two times.

There is no concept of Session variables in windows forms.

Create a Static class that holds the User name and password and any other variables needed across the application .

In your case it would be something like:

public static class LoginInfo
{
    public static string UserID;
}
Now you can access the UserID simply from anywhere in your code:

MessageBox.Show(LogInfo.UserID);
Or set the values after login like

LogInfo.UserID=TextBox1.Text;

use just this type of concept.