12talis source spawn monsters to another map

[HerpDerpNigga]

can someone give me a tip on how to add monsters to a map, for example i want them spawn in Training Ground (the id of the map is 1039), and how to make them drop some items i want?
i am using 12talis source
Ty
just give me a tip , where should i go in project files to make it work.

[12tails]

Screen.cs

[HerpDerpNigga]

but i can't find that class... Screen.cs