scaning code

Your requirement is not clear, do you want to read barcodes? Or do you want to scan a paper from an actual scanner? And where do the textboxes fit into your scenario?

If you want to read barcodes, you can use an sdk such as leadtools that will help you to deal with the barcode image. There are lots of examples and articles on the internet for reading barcodes such as the following:
https://social.msdn.microsoft.com/Forums/vstudio/en-US/7b915a12-153b-4f46-9010-317c521799a1/reading-barcode-using-vbnet-code?forum=vbgeneral

http://www.codeproject.com/Articles/278301/How-to-Read-Barcodes-from-Images-using-LEADTOOLS

If you mean something else, please provide more details.