It's helpful to reach out to an experienced local member.
I had help the first few times...
The gui is quite straight forward in ecuflash.
Just don't take any chances once flashing.
Eg you need a healthy battery, I'd advise backup battery /charger, a stable laptop/OS / software and plugins etc, power for the laptop, and never key off if the flash didn't work properly, reflash the saved tune if required first.