FFV Eventing help?

I've just started hacking FFV using ff6tools (disasm is beyond my skill level)
I'm playing with the events and i cannot figure out how to Set an event flag...
Ex: NPC says NPC Dialog 1 , but with event switch XXX being set says NPC Dialogue 2.
I understand the basic If else syntax, i just cannot figure out how to set a flag. 
Searched through github for keywords, didn't find anything or an existing post here.
Can someone educate me, or am I just missing something.