How to check if an item is obtained

[Osakawa]

I've made it to use OnReachingArea and go to next scene. However, now I put a chest with a special item in it and want the player to obtain the item before reach the "rescue point" area. (On reaching the area, the player wins the battle.) I don't know how to check if the item is obtained by the player. Can you offer me a hint in a few words?
Besides, I am trying to figure out how to set a variable in the first map scene and show it in the second map scene.
May I pay you some money for answering my future questions?

[CraigStern]

In general, the actions to create variables are all Set actions: SetVal, SetStr, and SetList being the three big ones. To reference them later, you'll want to use special characters like -VAL:x- and -STR:x-.

To check if a character has an item, you'll want to use one of two actions: IfItemGoTo or IfItemRun.