Without being mean mate, I think you should overlook the Engine Scripts page a little bit more. While we are here to help, we cannot always just give you code. Look through Amnesia, other people's Custom Stories, the wiki tutorials and previous forum posts. You have to learn what to do as well, not just rely on everybody else.
Regardless:
void OnStart()
{
SetEntityPlayerInteractCallback("", "interacted", false);
}
void interacted("name_of_entity_in_Level_Editor")
{
SetMessage(string& asTextCategory, string& asTextEntry, 0.0f);
}
(I think that works. Haven't tested it, but followed correct terms in setting it up)
You need to supply the TextCategory and TextEntry, according to your lang file, and change the name_of_entity_in_Level_Editor to the name of what you're interacting with.