You may refer to this 2 app notes, those will help you on getting started with your custom board (creating and customizing images) and download/debug using JTAG in normal and secure mode.
I have one more question regarding this. On reading the application note(AN12631), I saw that we need to connect the Lauterbach hardware to the board. I have a SEGGER JLink EDU with me. Will it be possible to use that?
You may refer to this 2 app notes, those will help you on getting started with your custom board (creating and customizing images) and download/debug using JTAG in normal and secure mode.