first create a Callback inside the OnStart() section of you map script. (I am assuming that you have set up everything needed for development...). The callback should be something like this one:
SetEntityCallbackFunc("note_generic_1","note_pickup1");
It makes the function note_pickup1 run when you pickup the note named note_generic_1
Then you have to define note_pickup1, put it outside of your OnStart() OnEnter() and OnLeave():
void note_pickup1(string& asName, string& asCallback)
{
//Put the thing you want to happen here, in your case, activate monster:
SetEntityActive("servant_grunt_1" , true); //true is active, false is not active, servant_grunt_1 is //the name of the monster
}
Ill post the rest (how you make the note text show) later if noone else helps you...Hope that will make the monster come running for you at least
.