New to NoFap. Many questions

hey, I’m new to NoFap. For some time I’ve had a masturbation adiction, more than a porn adiction.
I really don’t know where to get started besides of the 90 day experiment, but I have some questions about it:
-I don’t know what count as restart, I know what it is but not really what can or can’t do

-This is perhaps my biggest concern: I have a girlfriend, we have only tried to have sex once, and I couldn’t get an erection. I’m really scared to dissapoint her, and I wan’t to know if, having sex with her during my 90 day period may affect in some way my perfomance (suposing I already accomplish an erection)