How to make a macro

i have a red dragon 512 keyboard need help

The best instructions for getting started with KM are on this page, if you follow the first couple of links....

https://forum.keyboardmaestro.com/t/getting-started-with-keyboard-maestro-and-the-forum

Or, if you tell us exactly what you want to do, maybe we can help. Your model of keyboard is generally not a problem, as KM can work with all models.

Just try to make e button on loop for like 200 times

You could try these actions:
https://wiki.keyboardmaestro.com/action/Type_a_Keystroke
https://wiki.keyboardmaestro.com/action/Repeat