Need help with rpg maker xp

ok i have a lady standing outside her house and when u talk to her she tells you her husband is sick and she asks u to help. if u say yes she tells u to get her a potion and she will give u a key in return . i wanna make it so that when u give her the potion then she gives u a key. also i want it so that the next time u talk to her she says something else like have u found a potion yet. some1 plz help thnks also how do u put the picture of a character next to the mesage bar when they are talking