Transaction Codes to work with ABAP Transations

SE38 --> To Create Module Pool

SE51 --> Screen Painter

--> Screen Painter have layout. Layout is to design Applications in Screen Painter.

Flow logic have PBO and PAI

Flow Logic : It maintains communication between Application & Logic

SE93 --> To create Transaction code for Application.

In Real Time these T.Codes are not accessable. So, use SE80 to design Applications.