Windows based apilcation

I suggest your login form should not be the start up form. Inside your Main(), Application.Run(YourForm), YourForm will be the main form and then  you just have to add a new windows form in your project and call it on YourForm's Load event. The technique might be a little confusing but for me, it is the most clever way of doing it. You can't just use the LogInForm's ShowDialog Method because your login form should return some real information (credentials). Another method in the form will work and it should return the information you needed. I hope you get my point.