Could need some help

Hello, 

after a long time I and a friend of mine decided to play this game again.

We wanted to make a own map and there we wanted to add asteroids which are producing a few more ressources than normal ones. I knew it is possible to do it via notepad++ but i dont know how we can add those. It would be really nice if someone could help me / us a bit out. I wish everyone a nice day .

Your 

Slimy :)