Can someone teach me how to use DSemu step by step. Like how to load ROMs.

Start the emulator
File, Open DS

Browse through the file structure for your BIN or NDS rom.

Click Open.


The rom is now loaded and running.

At this point, you've probably either got a white or black screen, a freeze or a crash.

That is the most likely outcome.

A few homebrews will run (sort of).

If you're looking to run commercial games, forget it.
It was never developed far enough for that to happen.