Getting a key and using a key

[omnee]

So how do I make that when I go in a certain page I get an Item (Key) like:

Walking in the bushes you find a key! (And it adds a key to inventory)

AND:

A page that I MUST have a key to go in, otherwise it just says:

You do not have the required items to go there!


I am using Mysidia 1.3.1 and I can't find many mods cuz it's new, if anybody knows how to do this, please, tell me