How to take proper picture by using external flash?what is the mistake I did in capturing picture I'm a noob in photography I have nikon d5300
Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.
I think you are using too high a shutter speed. Consult the manual for your external flash and use the shutter speed which is supported by your external flash.