If you are complete beginner then forget about IDEs for now. You will learn more by working with an editor & compiler. IDEs will generate code and fix problems for you, but if you don't fully understand what they are doing and why, you will get into trouble. When, eventually, you are ready for an IDE there are only 2 that are widely used in commercial environments, NetBeans and Eclipse. They are both equally good, but the Java tutorials use NetBeans, and if you plan to work for IBM you will be using Eclipse.
For Each ctrl As Control In Me.Controls("pnlMainPanel").Controls
If ctrl.GetType Is GetType(System.Windows.Forms.Panel) Then
For Each subCtrl As Control In ctrl.Controls
If subCtrl.GetType Is GetType(System.Windows.Forms.TextBox) Then
If subCtrl.GetType Is ...