For the fishermen and any other NPCs(Non Playable Characters) that ask you if you want a free potion or ask you if they should do something(IE: the fisherman from the first map that asks you if he should go fishing)
1st Page
(Graphics)- Whichever you had chosen
(Trigger)- Action Key
(Movement)- (What ever you want)
(Event)- Message-(What ever)
Conditional Branch(Yes,No) ///This can be changed to what ever you want it to be
Condition-Yes
Message- (What ever)
Self Switch/Local Switch A = On
Condition-No
Message- (What ever)
2nd Page
(Precondition) Self Switch/Local Switch A = On
(Graphics)- Same as the one you used in the 1st Page
(Trigger)- Action Key
(Movement)- (Whatever you want)
(Event)- Message- (What ever)
For people who ask to join your party IE: the girl in the town
1st Page
(Graphics)- Whichever you had chosen
(Trigger)- Action Key
(Movement)- (What ever you want)
(Event)- Message-(Can I join your party)<-Change to what you want it to say
Conditional Branch(Yes,No)<-This can be changed to what ever you want it to be
Condition-Yes
Message- (What ever) <-Can be changed
Self Switch/Local Switch A = On
Condition-No
Message- (What ever) <-Can be changed
2nd Page
(Precondition) Self Switch/Local Switch A = On
(Graphics)- Same as the one you used in the 1st Page
(Trigger)- Auto Start (Parallel Process if you have any other events running)
(Movement)- (Whatever you want)
(Event)- Add Party Member-(Name)
(CAN ADD ANYTHING YOU WANT)
End Event
Message- (Name) joined your party <-I usually add this, just to make it unique
The end event is there so that after someone joins your party that event/person you were talking to dissapears and into your party
Hope that clears it up, if you get any errors or questions just ask
EDIT: Here is a basic Tutorial telling you what the Party and Item Changer do (as you asked)