ARK88
"Controls" is a collection that contains controls. If a control is a container control, it can have other controls in it. So, a form is a container control, a groupbox is a container control, a panel is a container control, etc... Each of those container controls has a "Controls" collection, which is all the controls contained within it. Remember when you accidentally placed one of your panels inside another If you would have checked the "Controls" collection of the outer panel you would have seen it had one control in its "Controls" collection (the misplaced panel). Its a parent-child type of relationship, where the parent container control can have zero or many child controls.
In your sample code, "bPortStatus" is an array. An array is a list of values. One advantage to arrays is that rather than declaring 15 variables, you can declare one array that has 15 elements (it can cut down on the amount of code you have to write). Specific values in an array are referenced using "[x]" where "x" is the index of the item you want. I'm not sure how you have "BIT_11" defined in your code, but its obvious by your error message that "BIT_" is not defined as an array, which is why you can't use the "[x]" syntax on it.
I can't really direct you to a book for more information on loops structured the way we've been discussing them... everything I've shared with you has been mostly things I've learned "on-the-job". If I were you, I'd look through the Visual Studio help file for more information about arrays, then try to write some code that uses them. After that, you might want to read-up a little bit about the Controls collection, then learn how to loop through them using "for" and "foreach" loops. A good sample application you could write to get you a little more acclimated would be a program that starts with the controls collection on the form, itterates through each control in that collection, then each controls collection of each of those controls, etc... so that it basically traverses every parent-child relationship on the entire form. It will familiarize you more with controls, control collections, loops, and maybe even recursive functions.